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Shu H, Parada I, Delgado A, Prince DA, Gu F. Increased excitatory connectivity and epileptiform activity in thrombospondin1/2 knockout mice following cortical trauma. Neurobiol Dis 2024; 200:106634. [PMID: 39122122 DOI: 10.1016/j.nbd.2024.106634] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 07/23/2024] [Accepted: 08/05/2024] [Indexed: 08/12/2024] Open
Abstract
Thrombospondins (TSPs) are astrocyte-secreted extracellular matrix proteins that play key roles as regulators of synaptogenesis in the central nervous system. We previously showed that TSP1/2 are upregulated in the partial neocortical isolation model ("undercut" or "UC" below) of posttraumatic epileptogenesis and may contribute to abnormal axonal sprouting, aberrant synaptogenesis and epileptiform discharges in the UC cortex. These results led to the hypothesis that posttraumatic epileptogeneis would be reduced in TSP1/2 knockout (TSP1/2 KO) mice. To test the hypothesis, we made UC lesions at P21, and subsequent experiments were conducted 14d later at P35. Ex vivo extracellular single or multi-electrode field potential recordings were obtained from layer V in cortical slices at P35 and in vivo video-EEGs of spontaneous epileptiform bursts were recorded to examine the effect of TSP1/2 deletion on epileptogenesis following cortical injury. Immunohistochemical experiments were performed to assess the effect of TSP1/2 KO + UC on the number of putative excitatory synapses and the expression of TSP4 and HEVIN, other astrocytic proteins known to up-regulate excitatory synapse formation. Unexpectedly, our results showed that, compared with WT + UC mice, TSP1/2 KO + UC mice displayed increased epileptiform activity, as indicated by 1) increased incidence and more rapid propagation of evoked and spontaneous epileptiform discharges in UC neocortical slices; 2) increased occurrence of spontaneous epileptiform discharges in vivo. There was an associated increase in the density of VLUT1/PSD95-IR colocalizations (putative excitatory synapses) and significantly upregulated TSP4- and HEVIN-IR in TSP1/2 KO + UC versus WT + UC mice. Results suggest that TSP1/2 deletion plays a potential epileptogenic role following neocortical injury, associated with compensatory upregulation of TSP4 and HEVIN, which may contribute to the increase in the density of excitatory synapses and resulting neural network hyperexcitability.
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Affiliation(s)
- Haifeng Shu
- Department of Neurosurgery, General Hospital of Western Theatre Command, College of Medicine of Southwest Jiaotong University, China
| | - Isabel Parada
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alex Delgado
- Department of Biological Sciences, University of North Texas, Denton, TX 76205, USA
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, USA.
| | - Feng Gu
- Department of Biological Sciences, University of North Texas, Denton, TX 76205, USA.
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2
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Asim M, Qianqian G, Waris A, Wang H, Lai Y, Chen X. Unraveling the role of cholecystokinin in epilepsy: Mechanistic insight into neuroplasticity. Neurochem Int 2024; 180:105870. [PMID: 39343303 DOI: 10.1016/j.neuint.2024.105870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2024] [Revised: 09/15/2024] [Accepted: 09/26/2024] [Indexed: 10/01/2024]
Abstract
Epilepsy is a disorder characterized by an imbalance between excitability and inhibition, leading to uncontrolled hyperexcitability of neurons in the central nervous system. Despite the prevalence of epileptic seizures, the underlying mechanisms driving this hyperexcitability remain poorly understood. This review article aims to enhance our understanding of the mechanisms of epilepsy, with a specific focus on the role of cholecystokinin (CCK) in this debilitating disease. We will begin with an introduction to the topic, followed by an examination of the role of GABAergic neurons and the synaptic plasticity mechanisms associated with seizures. As we delve deeper, we will elucidate how CCK and its receptors contribute to seizure behavior. Finally, we will discuss the CCK-dependent synaptic plasticity mechanisms and highlight their potential implications in seizure activity. Through a comprehensive examination of these aspects, this review provides valuable insights into the involvement of CCK and its receptors in epilepsy. By improving our understanding of the mechanisms underlying this condition, particularly the role of CCK, we aim to contribute to the development of more effective treatment strategies.
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Affiliation(s)
- Muhammad Asim
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong.
| | - Gao Qianqian
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Abdul Waris
- Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Huajie Wang
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Yuanying Lai
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong
| | - Xi Chen
- Department of Neuroscience, City University of Hong Kong, Kowloon Tong, Hong Kong; Department of Biomedical Science, City University of Hong Kong, Kowloon Tong, Hong Kong; Centre for Regenerative Medicine and Health, Hong Kong Institute of Science and Innovation, Chinese Academy of Sciences, Hong Kong
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3
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Shen Y, Shao M, Hao ZZ, Huang M, Xu N, Liu S. Multimodal Nature of the Single-cell Primate Brain Atlas: Morphology, Transcriptome, Electrophysiology, and Connectivity. Neurosci Bull 2024; 40:517-532. [PMID: 38194157 PMCID: PMC11003949 DOI: 10.1007/s12264-023-01160-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2023] [Accepted: 09/23/2023] [Indexed: 01/10/2024] Open
Abstract
Primates exhibit complex brain structures that augment cognitive function. The neocortex fulfills high-cognitive functions through billions of connected neurons. These neurons have distinct transcriptomic, morphological, and electrophysiological properties, and their connectivity principles vary. These features endow the primate brain atlas with a multimodal nature. The recent integration of next-generation sequencing with modified patch-clamp techniques is revolutionizing the way to census the primate neocortex, enabling a multimodal neuronal atlas to be established in great detail: (1) single-cell/single-nucleus RNA-seq technology establishes high-throughput transcriptomic references, covering all major transcriptomic cell types; (2) patch-seq links the morphological and electrophysiological features to the transcriptomic reference; (3) multicell patch-clamp delineates the principles of local connectivity. Here, we review the applications of these technologies in the primate neocortex and discuss the current advances and tentative gaps for a comprehensive understanding of the primate neocortex.
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Affiliation(s)
- Yuhui Shen
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Mingting Shao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Zhao-Zhe Hao
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Mengyao Huang
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Nana Xu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China
| | - Sheng Liu
- State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangdong Provincial Key Laboratory of Ophthalmology and Visual Science, Guangzhou, 510060, China.
- Guangdong Province Key Laboratory of Brain Function and Disease, Guangzhou, 510080, China.
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4
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Plutino S, Laghouati E, Jarre G, Depaulis A, Guillemain I, Bureau I. Barrel cortex development lacks a key stage of hyperconnectivity from deep to superficial layers in a rat model of Absence Epilepsy. Prog Neurobiol 2024; 234:102564. [PMID: 38244975 DOI: 10.1016/j.pneurobio.2023.102564] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2023] [Revised: 12/04/2023] [Accepted: 12/30/2023] [Indexed: 01/22/2024]
Abstract
During development of the sensory cortex, the ascending innervation from deep to upper layers provides a temporary scaffold for the construction of other circuits that remain at adulthood. Whether an alteration in this sequence leads to brain dysfunction in neuro-developmental diseases remains unknown. Using functional approaches in a genetic model of Absence Epilepsy (GAERS), we investigated in barrel cortex, the site of seizure initiation, the maturation of excitatory and inhibitory innervations onto layer 2/3 pyramidal neurons and cell organization into neuronal assemblies. We found that cortical development in GAERS lacks the early surge of connections originating from deep layers observed at the end of the second postnatal week in normal rats and the concomitant structuring into multiple assemblies. Later on, at seizure onset (1 month old), excitatory neurons are hyper-excitable in GAERS when compared to Wistar rats. These findings suggest that early defects in the development of connectivity could promote this typical epileptic feature and/or its comorbidities.
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Affiliation(s)
| | - Emel Laghouati
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
| | - Guillaume Jarre
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
| | - Antoine Depaulis
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
| | - Isabelle Guillemain
- Univ. Grenoble Alpes, Inserm, U1216, Grenoble Institut Neurosciences, 38000 Grenoble, France
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5
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Bernard C, Frauscher B, Gelinas J, Timofeev I. Sleep, oscillations, and epilepsy. Epilepsia 2023; 64 Suppl 3:S3-S12. [PMID: 37226640 PMCID: PMC10674035 DOI: 10.1111/epi.17664] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2023] [Revised: 04/27/2023] [Accepted: 05/23/2023] [Indexed: 05/26/2023]
Abstract
Sleep and wake are defined through physiological and behavioral criteria and can be typically separated into non-rapid eye movement (NREM) sleep stages N1, N2, and N3, rapid eye movement (REM) sleep, and wake. Sleep and wake states are not homogenous in time. Their properties vary during the night and day cycle. Given that brain activity changes as a function of NREM, REM, and wake during the night and day cycle, are seizures more likely to occur during NREM, REM, or wake at a specific time? More generally, what is the relationship between sleep-wake cycles and epilepsy? We will review specific examples from clinical data and results from experimental models, focusing on the diversity and heterogeneity of these relationships. We will use a top-down approach, starting with the general architecture of sleep, followed by oscillatory activities, and ending with ionic correlates selected for illustrative purposes, with respect to seizures and interictal spikes. The picture that emerges is that of complexity; sleep disruption and pathological epileptic activities emerge from reorganized circuits. That different circuit alterations can occur across patients and models may explain why sleep alterations and the timing of seizures during the sleep-wake cycle are patient-specific.
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Affiliation(s)
| | - Birgit Frauscher
- Montreal Neurological Institute and Hospital, McGill University, Montreal, Quebec, Canada
| | - Jennifer Gelinas
- Institute for Genomic Medicine, Columbia University Medical Center, New York, NY, USA
- Department of Neurology, Columbia University Medical Center, New York, NY, USA
| | - Igor Timofeev
- Faculté de Médecine, Département de Psychiatrie et de Neurosciences, Centre de Recherche CERVO, Université Laval, Québec, QC G1J2G3, Canada
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6
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Okoh J, Mays J, Bacq A, Oses-Prieto JA, Tyanova S, Chen CJ, Imanbeyev K, Doladilhe M, Zhou H, Jafar-Nejad P, Burlingame A, Noebels J, Baulac S, Costa-Mattioli M. Targeted suppression of mTORC2 reduces seizures across models of epilepsy. Nat Commun 2023; 14:7364. [PMID: 37963879 PMCID: PMC10645975 DOI: 10.1038/s41467-023-42922-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Accepted: 10/26/2023] [Indexed: 11/16/2023] Open
Abstract
Epilepsy is a neurological disorder that poses a major threat to public health. Hyperactivation of mTOR complex 1 (mTORC1) is believed to lead to abnormal network rhythmicity associated with epilepsy, and its inhibition is proposed to provide some therapeutic benefit. However, mTOR complex 2 (mTORC2) is also activated in the epileptic brain, and little is known about its role in seizures. Here we discover that genetic deletion of mTORC2 from forebrain neurons is protective against kainic acid-induced behavioral and EEG seizures. Furthermore, inhibition of mTORC2 with a specific antisense oligonucleotide robustly suppresses seizures in several pharmacological and genetic mouse models of epilepsy. Finally, we identify a target of mTORC2, Nav1.2, which has been implicated in epilepsy and neuronal excitability. Our findings, which are generalizable to several models of human seizures, raise the possibility that inhibition of mTORC2 may serve as a broader therapeutic strategy against epilepsy.
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Affiliation(s)
- James Okoh
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Jacqunae Mays
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Alexandre Bacq
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Juan A Oses-Prieto
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Stefka Tyanova
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | - Chien-Ju Chen
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Novartis Inc, Boston, MA, USA
| | - Khalel Imanbeyev
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
| | - Marion Doladilhe
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Hongyi Zhou
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA
| | | | - Alma Burlingame
- Departments of Chemistry and Pharmaceutical Chemistry, University of California San Fransisco, San Fransisco, CA, USA
| | - Jeffrey Noebels
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA
- Department of Molecular & Human Genetics, Baylor College of Medicine, Houston, TX, USA
- Department of Neurology, Baylor College of Medicine, Houston, TX, USA
| | - Stephanie Baulac
- Institut du Cerveau-Paris Brain Institute-ICM, Sorbonne Université, Inserm, CNRS, Hôpital de la Pitié Salpêtrière, F-75013, Paris, France
| | - Mauro Costa-Mattioli
- Department of Neuroscience, Baylor College of Medicine, Houston, TX, USA.
- Memory and Brain Research Center, Baylor College of Medicine, Houston, TX, USA.
- Altos Labs Inc, Bay Area Institute, Redwood City, CA, USA.
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7
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Fang M, Liu W, Tuo J, Liu M, Li F, Zhang L, Yu C, Xu Z. Advances in understanding the pathogenesis of post-traumatic epilepsy: a literature review. Front Neurol 2023; 14:1141434. [PMID: 37638179 PMCID: PMC10449544 DOI: 10.3389/fneur.2023.1141434] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2023] [Accepted: 07/14/2023] [Indexed: 08/29/2023] Open
Abstract
Severe head trauma can lead to seizures. Persistent epileptic seizures and their progression are associated with the severity of trauma. Although case reports have revealed that early use of anti-seizure drugs after trauma can prevent epilepsy, clinical case-control studies have failed to confirm this phenomenon. To date, many brain trauma models have been used to study the correlation between post-traumatic seizures and related changes in neural circuit function. According to these studies, neuronal and glial responses are activated immediately after brain trauma, usually leading to significant cell loss in injured brain regions. Over time, long-term changes in neural circuit tissues, especially in the neocortex and hippocampus, lead to an imbalance between excitatory and inhibitory neurotransmission and an increased risk of spontaneous seizures. These changes include alterations in inhibitory interneurons and the formation of new, over-recurrent excitatory synaptic connections. In this study, we review the progress of research related to post-traumatic epilepsy to better understand the mechanisms underlying the initiation and development of post-traumatic seizures and to provide theoretical references for the clinical treatment of post-traumatic seizures.
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Affiliation(s)
- Mingzhu Fang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Sichuan Provincial People’s Hospital Medical Group Chuantou Xichang Hospital, Xichang, China
| | - Wanyu Liu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Jinmei Tuo
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- Department of Nursing, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine of Zunyi Medical University, Zunyi, China
| | - Mei Liu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine of Zunyi Medical University, Zunyi, China
| | - Fangjing Li
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Lijia Zhang
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
| | - Changyin Yu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine of Zunyi Medical University, Zunyi, China
| | - Zucai Xu
- Department of Neurology, Affiliated Hospital of Zunyi Medical University, Zunyi, China
- The Collaborative Innovation Center of Tissue Damage Repair and Regeneration Medicine of Zunyi Medical University, Zunyi, China
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8
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Reiner A. Could theropod dinosaurs have evolved to a human level of intelligence? J Comp Neurol 2023; 531:975-1006. [PMID: 37029483 PMCID: PMC10106414 DOI: 10.1002/cne.25458] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2022] [Revised: 01/05/2023] [Accepted: 01/11/2023] [Indexed: 04/09/2023]
Abstract
Noting that some theropod dinosaurs had large brains, large grasping hands, and likely binocular vision, paleontologist Dale Russell suggested that a branch of these dinosaurs might have evolved to a human intelligence level, had dinosaurs not become extinct. I offer reasons why the likely pallial organization in dinosaurs would have made this improbable, based on four assumptions. First, it is assumed that achieving human intelligence requires evolving an equivalent of the about 200 functionally specialized cortical areas characteristic of humans. Second, it is assumed that dinosaurs had an avian nuclear type of pallial organization, in contrast to the mammalian cortical organization. Third, it is assumed that the interactions between the different neuron types making up an information processing unit within pallium are critical to its role in analyzing information. Finally, it is assumed that increasing axonal length between the neuron sets carrying out this operation impairs its efficacy. Based on these assumptions, I present two main reasons why dinosaur pallium might have been unable to add the equivalent of 200 efficiently functioning cortical areas. First, a nuclear pattern of pallial organization would require increasing distances between the neuron groups corresponding to the separate layers of any given mammalian cortical area, as more sets of nuclei equivalent to a cortical area are interposed between the existing sets, increasing axon length and thereby impairing processing efficiency. Second, because of its nuclear organization, dinosaur pallium could not reduce axon length by folding to bring adjacent areas closer together, as occurs in cerebral cortex.
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Affiliation(s)
- Anton Reiner
- Department of Anatomy and Neurobiology, University of Tennessee Health Science Center, Memphis, Tennessee, USA
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9
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Issa NP, Nunn KC, Wu S, Haider HA, Tao JX. Putative roles for homeostatic plasticity in epileptogenesis. Epilepsia 2023; 64:539-552. [PMID: 36617338 PMCID: PMC10015501 DOI: 10.1111/epi.17500] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Revised: 01/04/2023] [Accepted: 01/05/2023] [Indexed: 01/09/2023]
Abstract
Homeostatic plasticity allows neural circuits to maintain an average activity level while preserving the ability to learn new associations and efficiently transmit information. This dynamic process usually protects the brain from excessive activity, like seizures. However, in certain contexts, homeostatic plasticity might produce seizures, either in response to an acute provocation or more chronically as a driver of epileptogenesis. Here, we review three seizure conditions in which homeostatic plasticity likely plays an important role: acute drug withdrawal seizures, posttraumatic or disconnection epilepsy, and cyclic seizures. Identifying the homeostatic mechanisms active at different stages of development and in different circuits could allow better targeting of therapies, including determining when neuromodulation might be most effective, proposing ways to prevent epileptogenesis, and determining how to disrupt the cycle of recurring seizure clusters.
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Affiliation(s)
- Naoum P. Issa
- Comprehensive Epilepsy Center, Department of Neurology, 5841 S. Maryland Ave., MC 2030, University of Chicago, Chicago, IL 60637
| | | | - Shasha Wu
- Comprehensive Epilepsy Center, Department of Neurology, 5841 S. Maryland Ave., MC 2030, University of Chicago, Chicago, IL 60637
| | - Hiba A. Haider
- Comprehensive Epilepsy Center, Department of Neurology, 5841 S. Maryland Ave., MC 2030, University of Chicago, Chicago, IL 60637
| | - James X. Tao
- Comprehensive Epilepsy Center, Department of Neurology, 5841 S. Maryland Ave., MC 2030, University of Chicago, Chicago, IL 60637
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10
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Wei L, Ding M, Zhang Y, Wang H. Decoding transcriptional signatures of the association between free water and macroscale organizations in healthy adolescents. Neuroimage 2022; 261:119514. [PMID: 35901916 DOI: 10.1016/j.neuroimage.2022.119514] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Revised: 07/11/2022] [Accepted: 07/22/2022] [Indexed: 11/16/2022] Open
Abstract
We leveraged a novel index of diffusion MRI to investigate the relationships among cortical free water, macro-organizations and gene expression in healthy adults. Few research has been conducted to investigate the role of free water in the healthy adults due to it can easily be affected also by aging diseases. High quality data of 350 subjects from Human Connectome Project were used in our study. Cortical free water was estimated by using a bi-tensor model. The free water was high in the limbic, insular and somatosensory cortex, while being lower in motor and association cortex. The negative correlation between the free water and cortical thickness has been consistently identified in almost all the cortical regions. Negative correlation between the cortical free water and structural covariance (rho=-0.38, pspin=0.005) revealed the free water was sensitive to cortical heterogeneity. Using human gene expression dataset, we found the gene expression pattern of the relationship between the free water and cortical thickness spatially coupled with primary gradient of structural covariance network (rho=0.40, pspin=0.004). Our findings indicated the free water was sensitive to the cortical cellular status. The relationship between free water and macroscale organization also reflected hierarchal structures of cerebral cortex.
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Affiliation(s)
- Lei Wei
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, PR China.
| | - Ming Ding
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, PR China
| | - Yuwen Zhang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, PR China
| | - He Wang
- Institute of Science and Technology for Brain-Inspired Intelligence, Fudan University, Shanghai, PR China; Human Phenome Institute, Fudan University, Shanghai, PR China; Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, PR China.
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11
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Frankowski JC, Foik AT, Tierno A, Machhor JR, Lyon DC, Hunt RF. Traumatic brain injury to primary visual cortex produces long-lasting circuit dysfunction. Commun Biol 2021; 4:1297. [PMID: 34789835 PMCID: PMC8599505 DOI: 10.1038/s42003-021-02808-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2021] [Accepted: 10/25/2021] [Indexed: 01/20/2023] Open
Abstract
Primary sensory areas of the mammalian neocortex have a remarkable degree of plasticity, allowing neural circuits to adapt to dynamic environments. However, little is known about the effects of traumatic brain injury on visual circuit function. Here we used anatomy and in vivo electrophysiological recordings in adult mice to quantify neuron responses to visual stimuli two weeks and three months after mild controlled cortical impact injury to primary visual cortex (V1). We found that, although V1 remained largely intact in brain-injured mice, there was ~35% reduction in the number of neurons that affected inhibitory cells more broadly than excitatory neurons. V1 neurons showed dramatically reduced activity, impaired responses to visual stimuli and weaker size selectivity and orientation tuning in vivo. Our results show a single, mild contusion injury produces profound and long-lasting impairments in the way V1 neurons encode visual input. These findings provide initial insight into cortical circuit dysfunction following central visual system neurotrauma.
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Affiliation(s)
- Jan C. Frankowski
- grid.266093.80000 0001 0668 7243Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697 USA
| | - Andrzej T. Foik
- grid.413454.30000 0001 1958 0162Ophthalmic Biology Group, International Centre for Translational Eye Research, Institute of Physical Chemistry, Polish Academy of Sciences, Warsaw, Poland
| | - Alexa Tierno
- grid.266093.80000 0001 0668 7243Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697 USA
| | - Jiana R. Machhor
- grid.266093.80000 0001 0668 7243Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697 USA
| | - David C. Lyon
- grid.266093.80000 0001 0668 7243Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697 USA
| | - Robert F. Hunt
- grid.266093.80000 0001 0668 7243Department of Anatomy & Neurobiology, University of California, Irvine, CA 92697 USA
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12
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Li A, Huynh C, Fitzgerald Z, Cajigas I, Brusko D, Jagid J, Claudio AO, Kanner AM, Hopp J, Chen S, Haagensen J, Johnson E, Anderson W, Crone N, Inati S, Zaghloul KA, Bulacio J, Gonzalez-Martinez J, Sarma SV. Neural fragility as an EEG marker of the seizure onset zone. Nat Neurosci 2021; 24:1465-1474. [PMID: 34354282 PMCID: PMC8547387 DOI: 10.1038/s41593-021-00901-w] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 06/30/2021] [Indexed: 02/07/2023]
Abstract
Over 15 million patients with epilepsy worldwide do not respond to drugs. Successful surgical treatment requires complete removal or disconnection of the seizure onset zone (SOZ), brain region(s) where seizures originate. Unfortunately, surgical success rates vary between 30 and 70% because no clinically validated biological marker of the SOZ exists. We develop and retrospectively validate a new electroencephalogram (EEG) marker-neural fragility-in a retrospective analysis of 91 patients by using neural fragility of the annotated SOZ as a metric to predict surgical outcomes. Fragility predicts 43 out of 47 surgical failures, with an overall prediction accuracy of 76% compared with the accuracy of clinicians at 48% (successful outcomes). In failed outcomes, we identify fragile regions that were untreated. When compared to 20 EEG features proposed as SOZ markers, fragility outperformed in predictive power and interpretability, which suggests neural fragility as an EEG biomarker of the SOZ.
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Affiliation(s)
- Adam Li
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA.
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA.
| | - Chester Huynh
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
| | | | - Iahn Cajigas
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Damian Brusko
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jonathan Jagid
- Department of Neurosurgery, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Angel O Claudio
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Andres M Kanner
- Department of Neurology, University of Miami Miller School of Medicine, Miami, FL, USA
| | - Jennifer Hopp
- Neurology, University of Maryland Medical Center, Baltimore, MD, USA
| | - Stephanie Chen
- Neurology, University of Maryland Medical Center, Baltimore, MD, USA
| | | | - Emily Johnson
- Neurology, Johns Hopkins Hospital, Baltimore, MD, USA
| | | | - Nathan Crone
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
- Neurology, Johns Hopkins Hospital, Baltimore, MD, USA
| | - Sara Inati
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Kareem A Zaghloul
- Surgical Neurology Branch, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Juan Bulacio
- Epilepsy Center, Cleveland Clinic, Cleveland, OH, USA
| | - Jorge Gonzalez-Martinez
- Neurosurgery and Epilepsy Center, University of Pittsburgh Medical Center, Pittsburgh, PA, USA
| | - Sridevi V Sarma
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, USA
- Institute for Computational Medicine, Johns Hopkins University, Baltimore, MD, USA
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13
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Wang YH, Huang TL, Chen X, Yu SX, Li W, Chen T, Li Y, Kuang YQ, Shu HF. Glioma-Derived TSP2 Promotes Excitatory Synapse Formation and Results in Hyperexcitability in the Peritumoral Cortex of Glioma. J Neuropathol Exp Neurol 2021; 80:137-149. [PMID: 33382873 DOI: 10.1093/jnen/nlaa149] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Seizures are common in patients with glioma, especially low-grade glioma (LGG). However, the epileptogenic mechanisms are poorly understood. Recent evidence has indicated that abnormal excitatory synaptogenesis plays an important role in epileptogenesis. The thrombospondin (TSP) family is a key regulator of synaptogenesis. Thus, this study aimed to elucidate the role of TSP2 in epileptogenesis in glioma-related epilepsy. The expression of TSP2 was increased in tumor tissue specimens from LGG patients, and this increase may have contributed to an increase in the density of spines and excitatory synapses in the peritumoral area. A glioma cell-implanted rat model was established by stereotactic implantation of wild-type TSP2-expressing, TSP2-overexpressing or TSP2-knockout C6 cells into the neocortex. Similarly, an increase in the density of excitatory synapses was also observed in the peritumoral area of the implanted tumor. In addition, epileptiform discharges occurred in the peritumoral cortex and were positively correlated with the TSP2 level in glioma tissues. Moreover, α2δ1/Rac1 signaling was enhanced in the peritumoral region, and treatment with the α2δ1 antagonist gabapentin inhibited epileptiform discharges in the peritumoral cortex. In conclusion, glioma-derived TSP2 promotes excitatory synapse formation, probably via the α2δ1/Rac1 signaling pathway, resulting in hyperexcitability in the peritumoral cortical networks, which may provide new insight into the epileptogenic mechanisms underlying glioma-related epilepsy.
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Affiliation(s)
- Yao-Hui Wang
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China.,College of Medicine, Southwest Jiaotong University, Chengdu, China
| | - Tian-Lan Huang
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China.,College of Medicine, Southwest Jiaotong University, Chengdu, China
| | - Xin Chen
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Si-Xun Yu
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Wei Li
- Central Lab, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Tao Chen
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Yang Li
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Yong-Qin Kuang
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China
| | - Hai-Feng Shu
- From the Department of Neurosurgery, General Hospital of Western Theater Command of PLA, Sichuan Province, China.,College of Medicine, Southwest Jiaotong University, Chengdu, China
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14
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Lee CH, Le JT, Ballester-Rosado CJ, Anderson AE, Swann JW. Neocortical Slow Oscillations Implicated in the Generation of Epileptic Spasms. Ann Neurol 2021; 89:226-241. [PMID: 33068018 PMCID: PMC7855630 DOI: 10.1002/ana.25935] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Revised: 09/23/2020] [Accepted: 10/12/2020] [Indexed: 11/09/2022]
Abstract
OBJECTIVE Epileptic spasms are a hallmark of severe seizure disorders. The neurophysiological mechanisms and the neuronal circuit(s) that generate these seizures are unresolved and are the focus of studies reported here. METHODS In the tetrodotoxin model, we used 16-channel microarrays and microwires to record electrophysiological activity in neocortex and thalamus during spasms. Chemogenetic activation was used to examine the role of neocortical pyramidal cells in generating spasms. Comparisons were made to recordings from infantile spasm patients. RESULTS Current source density and simultaneous multiunit activity analyses indicate that the ictal events of spasms are initiated in infragranular cortical layers. A dramatic pause of neuronal activity was recorded immediately prior to the onset of spasms. This preictal pause is shown to share many features with the down states of slow wave sleep. In addition, the ensuing interictal up states of slow wave rhythms are more intense in epileptic than control animals and occasionally appear sufficient to initiate spasms. Chemogenetic activation of neocortical pyramidal cells supported these observations, as it increased slow oscillations and spasm numbers and clustering. Recordings also revealed a ramp-up in the number of neocortical slow oscillations preceding spasms, which was also observed in infantile spasm patients. INTERPRETATION Our findings provide evidence that epileptic spasms can arise from the neocortex and reveal a previously unappreciated interplay between brain state physiology and spasm generation. The identification of neocortical up states as a mechanism capable of initiating epileptic spasms will likely provide new targets for interventional therapies. ANN NEUROL 2021;89:226-241.
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Affiliation(s)
- Chih-hong Lee
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- The Cain Foundation Laboratories, The Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, USA
- Department of Neurology, Chang Gung Memorial Hospital Linkou Medical Center and Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - John T. Le
- The Cain Foundation Laboratories, The Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Carlos J. Ballester-Rosado
- The Cain Foundation Laboratories, The Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
| | - Anne E. Anderson
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- The Cain Foundation Laboratories, The Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
- Department of Neurology, Baylor College of Medicine, Houston, Texas, USA
| | - John W. Swann
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
- The Cain Foundation Laboratories, The Jan and Dan Duncan Neurological Research Institute, Texas Children’s Hospital, Houston, Texas, USA
- Department of Pediatrics, Baylor College of Medicine, Houston, Texas, USA
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15
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Targeting BDNF/TrkB pathways for preventing or suppressing epilepsy. Neuropharmacology 2019; 167:107734. [PMID: 31377199 DOI: 10.1016/j.neuropharm.2019.107734] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 07/25/2019] [Accepted: 08/01/2019] [Indexed: 12/15/2022]
Abstract
Traumatic brain injury (TBI) and status epilepticus (SE) have both been linked to development of human epilepsy. Although distinct etiologies, current research has suggested the convergence of molecular mechanisms underlying epileptogenesis following these insults. One such mechanism involves the neurotrophin brain-derived neurotrophic factor (BDNF) and its high-affinity receptor, tropomyosin related kinase B (TrkB). In this review, we focus on currently available data regarding the pathophysiologic role of BDNF/TrkB signaling in epilepsy development. We specifically examine the axonal injury and SE epilepsy models, two animal models that recapitulate many aspects of TBI- and SE-induced epilepsy in humans respectively. Thereafter, we discuss aspiring strategies for targeting BDNF/TrkB signaling so as to prevent epilepsy following an insult or suppress its expression once developed. This article is part of the special issue entitled 'New Epilepsy Therapies for the 21st Century - From Antiseizure Drugs to Prevention, Modification and Cure of Epilepsy'.
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16
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González OC, Krishnan GP, Timofeev I, Bazhenov M. Ionic and synaptic mechanisms of seizure generation and epileptogenesis. Neurobiol Dis 2019; 130:104485. [PMID: 31150792 DOI: 10.1016/j.nbd.2019.104485] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 05/23/2019] [Accepted: 05/27/2019] [Indexed: 01/09/2023] Open
Abstract
The biophysical mechanisms underlying epileptogenesis and the generation of seizures remain to be better understood. Among many factors triggering epileptogenesis are traumatic brain injury breaking normal synaptic homeostasis and genetic mutations disrupting ionic concentration homeostasis. Impairments in these mechanisms, as seen in various brain diseases, may push the brain network to a pathological state characterized by increased susceptibility to unprovoked seizures. Here, we review recent computational studies exploring the roles of ionic concentration dynamics in the generation, maintenance, and termination of seizures. We further discuss how ionic and synaptic homeostatic mechanisms may give rise to conditions which prime brain networks to exhibit recurrent spontaneous seizures and epilepsy.
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Affiliation(s)
- Oscar C González
- Neurosciences Graduate Program, University of California, San Diego, CA 92093, United States of America; Department of Medicine, University of California, San Diego, CA 92093, United States of America
| | - Giri P Krishnan
- Department of Medicine, University of California, San Diego, CA 92093, United States of America
| | - Igor Timofeev
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), 2601 de la Canardière, Québec, QC, Canada; Department of Psychiatry and Neuroscience, Université Laval, Québec, QC, Canada
| | - Maxim Bazhenov
- Neurosciences Graduate Program, University of California, San Diego, CA 92093, United States of America; Department of Medicine, University of California, San Diego, CA 92093, United States of America.
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17
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Slater BJ, Sons SK, Yudintsev G, Lee CM, Llano DA. Thalamocortical and Intracortical Inputs Differentiate Layer-Specific Mouse Auditory Corticocollicular Neurons. J Neurosci 2019; 39:256-270. [PMID: 30361396 PMCID: PMC6325253 DOI: 10.1523/jneurosci.3352-17.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2017] [Revised: 10/10/2018] [Accepted: 10/12/2018] [Indexed: 11/21/2022] Open
Abstract
Long-range descending projections from the auditory cortex play key roles in shaping response properties in the inferior colliculus. The auditory corticocollicular projection is massive and heterogeneous, with axons emanating from cortical layers 5 and 6, and plays a key role in directing plastic changes in the inferior colliculus. However, little is known about the cortical and thalamic networks within which corticocollicular neurons are embedded. Here, laser scanning photostimulation glutamate uncaging and photoactivation of channelrhodopsin-2 were used to probe the local and long-range network differences between preidentified layer 5 and layer 6 auditory corticocollicular neurons from male and female mice in vitro Layer 5 corticocollicular neurons were found to vertically integrate supragranular excitatory and inhibitory input to a substantially greater degree than their layer 6 counterparts. In addition, all layer 5 corticocollicular neurons received direct and large thalamic inputs from channelrhodopsin-2-labeled thalamocortical fibers, whereas such inputs were less common in layer 6 corticocollicular neurons. Finally, a new low-calcium/synaptic blockade approach to separate direct from indirect inputs using laser photostimulation was validated. These data demonstrate that layer 5 and 6 corticocollicular neurons receive distinct sets of cortical and thalamic inputs, supporting the hypothesis that they have divergent roles in modulating the inferior colliculus. Furthermore, the direct connection between the auditory thalamus and layer 5 corticocollicular neurons reveals a novel and rapid link connecting ascending and descending pathways.SIGNIFICANCE STATEMENT Descending projections from the cortex play a critical role in shaping the response properties of sensory neurons. The projection from the auditory cortex to the inferior colliculus is a massive, yet poorly understood, pathway emanating from two distinct cortical layers. Here we show, using a range of optical techniques, that mouse auditory corticocollicular neurons from different layers are embedded into different cortical and thalamic networks. Specifically, we observed that layer 5 corticocollicular neurons integrate information across cortical lamina and receive direct thalamic input. The latter connection provides a hyperdirect link between acoustic sensation and descending control, thus demonstrating a novel mechanism for rapid "online" modulation of sensory perception.
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Affiliation(s)
- Bernard J Slater
- Neuroscience Program and
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801
| | - Stacy K Sons
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, and
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801
| | - Georgiy Yudintsev
- Neuroscience Program and
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801
| | - Christopher M Lee
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, and
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801
| | - Daniel A Llano
- Neuroscience Program and
- Department of Molecular and Integrative Physiology, University of Illinois Urbana-Champaign, Urbana, Illinois 61801, and
- Beckman Institute for Advanced Science and Technology, Urbana, Illinois 61801
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18
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Seeman SC, Campagnola L, Davoudian PA, Hoggarth A, Hage TA, Bosma-Moody A, Baker CA, Lee JH, Mihalas S, Teeter C, Ko AL, Ojemann JG, Gwinn RP, Silbergeld DL, Cobbs C, Phillips J, Lein E, Murphy G, Koch C, Zeng H, Jarsky T. Sparse recurrent excitatory connectivity in the microcircuit of the adult mouse and human cortex. eLife 2018; 7:e37349. [PMID: 30256194 PMCID: PMC6158007 DOI: 10.7554/elife.37349] [Citation(s) in RCA: 90] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2018] [Accepted: 08/21/2018] [Indexed: 01/09/2023] Open
Abstract
Generating a comprehensive description of cortical networks requires a large-scale, systematic approach. To that end, we have begun a pipeline project using multipatch electrophysiology, supplemented with two-photon optogenetics, to characterize connectivity and synaptic signaling between classes of neurons in adult mouse primary visual cortex (V1) and human cortex. We focus on producing results detailed enough for the generation of computational models and enabling comparison with future studies. Here, we report our examination of intralaminar connectivity within each of several classes of excitatory neurons. We find that connections are sparse but present among all excitatory cell classes and layers we sampled, and that most mouse synapses exhibited short-term depression with similar dynamics. Synaptic signaling between a subset of layer 2/3 neurons, however, exhibited facilitation. These results contribute to a body of evidence describing recurrent excitatory connectivity as a conserved feature of cortical microcircuits.
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Affiliation(s)
| | | | | | - Alex Hoggarth
- Allen Institute for Brain ScienceSeattleUnited States
| | - Travis A Hage
- Allen Institute for Brain ScienceSeattleUnited States
| | | | | | - Jung Hoon Lee
- Allen Institute for Brain ScienceSeattleUnited States
| | | | | | - Andrew L Ko
- Regional Epilepsy Center at Harborview Medical CenterSeattleUnited States
- Department of Neurological SurgeryUniversity of Washington School of MedicineSeattleUnited States
| | - Jeffrey G Ojemann
- Regional Epilepsy Center at Harborview Medical CenterSeattleUnited States
- Department of Neurological SurgeryUniversity of Washington School of MedicineSeattleUnited States
| | - Ryder P Gwinn
- Epilepsy Surgery and Functional NeurosurgerySwedish Neuroscience InstituteSeattleUnited States
| | - Daniel L Silbergeld
- Department of Neurological SurgeryUniversity of Washington School of MedicineSeattleUnited States
| | - Charles Cobbs
- The Ben and Catherine Ivy Center for Advanced Brain Tumor TreatmentSwedish Neuroscience InstituteSeattleUnited States
| | - John Phillips
- Allen Institute for Brain ScienceSeattleUnited States
| | - Ed Lein
- Allen Institute for Brain ScienceSeattleUnited States
| | - Gabe Murphy
- Allen Institute for Brain ScienceSeattleUnited States
| | - Christof Koch
- Allen Institute for Brain ScienceSeattleUnited States
| | - Hongkui Zeng
- Allen Institute for Brain ScienceSeattleUnited States
| | - Tim Jarsky
- Allen Institute for Brain ScienceSeattleUnited States
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19
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Takahashi DK, Jin S, Prince DA. Gabapentin Prevents Progressive Increases in Excitatory Connectivity and Epileptogenesis Following Neocortical Trauma. Cereb Cortex 2018; 28:2725-2740. [PMID: 28981586 PMCID: PMC6041890 DOI: 10.1093/cercor/bhx152] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 05/30/2017] [Accepted: 06/01/2017] [Indexed: 11/12/2022] Open
Abstract
Neocortical injury initiates a cascade of events, some of which result in maladaptive epileptogenic reorganization of surviving neural circuits. Research focused on molecular and organizational changes that occur following trauma may reveal processes that underlie human post-traumatic epilepsy (PTE), a common and unfortunate consequence of traumatic brain injury. The latency between injury and development of PTE provides an opportunity for prophylactic intervention, once the key underlying mechanisms are understood. In rodent neocortex, injury to pyramidal neurons promotes axonal sprouting, resulting in increased excitatory circuitry that is one important factor promoting epileptogenesis. We used laser-scanning photostimulation of caged glutamate and whole-cell recordings in in vitro slices from injured neocortex to assess formation of new excitatory synapses, a process known to rely on astrocyte-secreted thrombospondins (TSPs), and to map the distribution of maladaptive circuit reorganization. We show that this reorganization is centered principally in layer V and associated with development of epileptiform activity. Short-term blockade of the synaptogenic effects of astrocyte-secreted TSPs with gabapentin (GBP) after injury suppresses the new excitatory connectivity and epileptogenesis for at least 2 weeks. Results reveal that aberrant circuit rewiring is progressive in vivo and provide further rationale for prophylactic anti-epileptogenic use of gabapentinoids following cortical trauma.
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Affiliation(s)
- D K Takahashi
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - Sha Jin
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
| | - D A Prince
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA, USA
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20
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de la Tremblaye PB, O'Neil DA, LaPorte MJ, Cheng JP, Beitchman JA, Thomas TC, Bondi CO, Kline AE. Elucidating opportunities and pitfalls in the treatment of experimental traumatic brain injury to optimize and facilitate clinical translation. Neurosci Biobehav Rev 2018; 85:160-175. [PMID: 28576511 PMCID: PMC5709241 DOI: 10.1016/j.neubiorev.2017.05.022] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/12/2017] [Indexed: 12/19/2022]
Abstract
The aim of this review is to discuss the research presented in a symposium entitled "Current progress in characterizing therapeutic strategies and challenges in experimental CNS injury" which was presented at the 2016 International Behavioral Neuroscience Society annual meeting. Herein we discuss diffuse and focal traumatic brain injury (TBI) and ensuing chronic behavioral deficits as well as potential rehabilitative approaches. We also discuss the effects of stress on executive function after TBI as well as the response of the endocrine system and regulatory feedback mechanisms. The role of the endocannabinoids after CNS injury is also discussed. Finally, we conclude with a discussion of antipsychotic and antiepileptic drugs, which are provided to control TBI-induced agitation and seizures, respectively. The review consists predominantly of published data.
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Affiliation(s)
- Patricia B de la Tremblaye
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Darik A O'Neil
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Megan J LaPorte
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Jeffrey P Cheng
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States
| | - Joshua A Beitchman
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, United States; Department of Child Health, University of Arizona College of Medicine, Phoenix, AZ, United States; Midwestern University, Glendale, AZ, United States
| | - Theresa Currier Thomas
- Barrow Neurological Institute at Phoenix Children's Hospital, Phoenix, AZ, United States; Department of Child Health, University of Arizona College of Medicine, Phoenix, AZ, United States; Phoenix VA Healthcare System, Phoenix, AZ, United States
| | - Corina O Bondi
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States; Department of Neurobiology, University of Pittsburgh, Pittsburgh, PA, United States
| | - Anthony E Kline
- Department of Physical Medicine & Rehabilitation, University of Pittsburgh, Pittsburgh, PA, United States; Safar Center for Resuscitation Research, University of Pittsburgh, Pittsburgh, PA, United States; Center for Neuroscience, University of Pittsburgh, Pittsburgh, PA, United States; Center for the Neural Basis of Cognition, University of Pittsburgh, Pittsburgh, PA, United States; Department of Critical Care Medicine, University of Pittsburgh, Pittsburgh, PA, United States; Department of Psychology, University of Pittsburgh, Pittsburgh, PA, United States.
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21
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Anastasiades PG, Marques‐Smith A, Butt SJB. Studies of cortical connectivity using optical circuit mapping methods. J Physiol 2018; 596:145-162. [PMID: 29110301 PMCID: PMC5767689 DOI: 10.1113/jp273463] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2017] [Accepted: 10/11/2017] [Indexed: 11/08/2022] Open
Abstract
An important consideration when probing the function of any neuron is to uncover the source of synaptic input onto the cell, its intrinsic physiology and efferent targets. Over the years, electrophysiological approaches have generated considerable insight into these properties in a variety of cortical neuronal subtypes and circuits. However, as researchers explore neuronal function in greater detail, they are increasingly turning to optical techniques to bridge the gap between local network interactions and behaviour. The application of optical methods has increased dramatically over the past decade, spurred on by the optogenetic revolution. In this review, we provide an account of recent innovations, providing researchers with a primer detailing circuit mapping strategies in the cerebral cortex. We will focus on technical aspects of performing neurotransmitter uncaging and channelrhodopsin-assisted circuit mapping, with the aim of identifying common pitfalls that can negatively influence the collection of reliable data.
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22
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Xiong W, Ping X, Ripsch MS, Chavez GSC, Hannon HE, Jiang K, Bao C, Jadhav V, Chen L, Chai Z, Ma C, Wu H, Feng J, Blesch A, White FA, Jin X. Enhancing excitatory activity of somatosensory cortex alleviates neuropathic pain through regulating homeostatic plasticity. Sci Rep 2017; 7:12743. [PMID: 28986567 PMCID: PMC5630599 DOI: 10.1038/s41598-017-12972-6] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Accepted: 09/18/2017] [Indexed: 01/06/2023] Open
Abstract
Central sensitization and network hyperexcitability of the nociceptive system is a basic mechanism of neuropathic pain. We hypothesize that development of cortical hyperexcitability underlying neuropathic pain may involve homeostatic plasticity in response to lesion-induced somatosensory deprivation and activity loss, and can be controlled by enhancing cortical activity. In a mouse model of neuropathic pain, in vivo two-photon imaging and patch clamp recording showed initial loss and subsequent recovery and enhancement of spontaneous firings of somatosensory cortical pyramidal neurons. Unilateral optogenetic stimulation of cortical pyramidal neurons both prevented and reduced pain-like behavior as detected by bilateral mechanical hypersensitivity of hindlimbs, but corpus callosotomy eliminated the analgesic effect that was ipsilateral, but not contralateral, to optogenetic stimulation, suggesting involvement of inter-hemispheric excitatory drive in this effect. Enhancing activity by focally blocking cortical GABAergic inhibition had a similar relieving effect on the pain-like behavior. Patch clamp recordings from layer V pyramidal neurons showed that optogenetic stimulation normalized cortical hyperexcitability through changing neuronal membrane properties and reducing frequency of excitatory postsynaptic events. We conclude that development of neuropathic pain involves abnormal homeostatic activity regulation of somatosensory cortex, and that enhancing cortical excitatory activity may be a novel strategy for preventing and controlling neuropathic pain.
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Affiliation(s)
- Wenhui Xiong
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Xingjie Ping
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Matthew S Ripsch
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Grace Santa Cruz Chavez
- Department of Biomedical Engineering, Purdue School of Engineering and Technology. IUPUI, Indianapolis, USA
| | - Heidi Elise Hannon
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Kewen Jiang
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Neurology, Children's Hospital, Zhejiang University School of Medicine, Hangzhou, China
| | - Chunhui Bao
- Shanghai Research Institute of Acupuncture-Moxibustion and Meridian, Shanghai, China
| | - Vaishnavi Jadhav
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Lifang Chen
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Department of Acupuncture, Zhejiang Traditional Chinese Medical University and the Third Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Zhi Chai
- Research Center of Neurobiology, Shanxi University of Traditional Chinese Medicine, Taiyuan, China
| | - Cungen Ma
- Research Center of Neurobiology, Shanxi University of Traditional Chinese Medicine, Taiyuan, China
| | - Huangan Wu
- Shanghai Research Institute of Acupuncture-Moxibustion and Meridian, Shanghai, China
| | - Jianqiao Feng
- Department of Acupuncture, Zhejiang Traditional Chinese Medical University and the Third Affiliated Hospital, Hangzhou, Zhejiang, China
| | - Armin Blesch
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA
| | - Fletcher A White
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Anesthesia, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Research and Development Services, Richard L. Roudebush VA Medical Center, Indianapolis, IN 46202, USA.
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute. Indiana University School of Medicine, Indianapolis, IN, 46202, USA.
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23
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Gu F, Parada I, Shen F, Li J, Bacci A, Graber K, Taghavi RM, Scalise K, Schwartzkroin P, Wenzel J, Prince DA. Structural alterations in fast-spiking GABAergic interneurons in a model of posttraumatic neocortical epileptogenesis. Neurobiol Dis 2017; 108:100-114. [PMID: 28823934 DOI: 10.1016/j.nbd.2017.08.008] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2017] [Revised: 08/11/2017] [Accepted: 08/16/2017] [Indexed: 01/22/2023] Open
Abstract
Electrophysiological experiments in the partial cortical isolation ("undercut" or "UC") model of injury-induced neocortical epileptogenesis have shown alterations in GABAergic synaptic transmission attributable to abnormalities in presynaptic terminals. To determine whether the decreased inhibition was associated with structural abnormalities in GABAergic interneurons, we used immunocytochemical techniques, confocal microscopy and EM in UC and control sensorimotor rat cortex to analyze structural alterations in fast-spiking parvalbumin-containing interneurons and pyramidal (Pyr) cells of layer V. Principle findings were: 1) there were no decreases in counts of parvalbumin (PV)- or GABA-immunoreactive interneurons in UC cortex, however there were significant reductions in expression of VGAT and GAD-65 and -67 in halos of GABAergic terminals around Pyr somata in layer V. 2) Consistent with previous results, somatic size and density of Pyr cells was decreased in infragranular layers of UC cortex. 3) Dendrites of biocytin-filled FS interneurons were significantly decreased in volume. 4) There were decreases in the size and VGAT content of GABAergic boutons in axons of biocytin-filled FS cells in the UC, together with a decrease in colocalization with postsynaptic gephyrin, suggesting a reduction in GABAergic synapses. Quantitative EM of layer V Pyr somata confirmed the reduction in inhibitory synapses. 5) There were marked and lasting reductions in brain derived neurotrophic factor (BDNF)-IR and -mRNA in Pyr cells and decreased TrkB-IR on PV cells in UC cortex. 6) Results lead to the hypothesis that reduction in trophic support by BDNF derived from Pyr cells may contribute to the regressive changes in axonal terminals and dendrites of FS cells in the UC cortex and decreased GABAergic inhibition. SIGNIFICANCE Injury to cortical structures is a major cause of epilepsy, accounting for about 20% of cases in the general population, with an incidence as high as ~50% among brain-injured personnel in wartime. Loss of GABAergic inhibitory interneurons is a significant pathophysiological factor associated with epileptogenesis following brain trauma and other etiologies. Results of these experiments show that the largest population of cortical interneurons, the parvalbumin-containing fast-spiking (FS) interneurons, are preserved in the partial neocortical isolation model of partial epilepsy. However, axonal terminals of these cells are structurally abnormal, have decreased content of GABA synthetic enzymes and vesicular GABA transporter and make fewer synapses onto pyramidal neurons. These structural abnormalities underlie defects in GABAergic neurotransmission that are a key pathophysiological factor in epileptogenesis found in electrophysiological experiments. BDNF, and its TrkB receptor, key factors for maintenance of interneurons and pyramidal neurons, are decreased in the injured cortex. Results suggest that supplying BDNF to the injured epileptogenic brain may reverse the structural and functional abnormalities in the parvalbumin FS interneurons and provide an antiepileptogenic therapy.
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Affiliation(s)
- Feng Gu
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Isabel Parada
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Fran Shen
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Judith Li
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Alberto Bacci
- ICM - Hôpital Pitié Salpêtrière, 7, bd de l'hôpital, 75013 Paris, France
| | - Kevin Graber
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Reza Moein Taghavi
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Karina Scalise
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States
| | - Philip Schwartzkroin
- Department of Neurological Surgery, University of California, Davis, United States
| | - Jurgen Wenzel
- Department of Neurological Surgery, University of California, Davis, United States
| | - David A Prince
- Epilepsy Research Laboratories, Stanford Univ. Sch. of Medicine, United States.
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24
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Ordaz JD, Wu W, Xu XM. Optogenetics and its application in neural degeneration and regeneration. Neural Regen Res 2017; 12:1197-1209. [PMID: 28966628 PMCID: PMC5607808 DOI: 10.4103/1673-5374.213532] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/11/2017] [Indexed: 12/30/2022] Open
Abstract
Neural degeneration and regeneration are important topics in neurological diseases. There are limited options for therapeutic interventions in neurological diseases that provide simultaneous spatial and temporal control of neurons. This drawback increases side effects due to non-specific targeting. Optogenetics is a technology that allows precise spatial and temporal control of cells. Therefore, this technique has high potential as a therapeutic strategy for neurological diseases. Even though the application of optogenetics in understanding brain functional organization and complex behaviour states have been elaborated, reviews of its therapeutic potential especially in neurodegeneration and regeneration are still limited. This short review presents representative work in optogenetics in disease models such as spinal cord injury, multiple sclerosis, epilepsy, Alzheimer's disease and Parkinson's disease. It is aimed to provide a broader perspective on optogenetic therapeutic potential in neurodegeneration and neural regeneration.
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Affiliation(s)
- Josue D. Ordaz
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
- Goodman Campbell Brain and Spine, Indianapolis, Indiana, USA
| | - Wei Wu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
- Goodman Campbell Brain and Spine, Indianapolis, Indiana, USA
| | - Xiao-Ming Xu
- Spinal Cord and Brain Injury Research Group, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Neurological Surgery, Indiana University School of Medicine, Indianapolis, IN, USA
- Goodman Campbell Brain and Spine, Indianapolis, Indiana, USA
- Department of Anatomy and Cell Biology, Indiana University School of Medicine, Indianapolis, IN, USA
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25
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Faria LC, Gu F, Parada I, Barres B, Luo ZD, Prince DA. Epileptiform activity and behavioral arrests in mice overexpressing the calcium channel subunit α2δ-1. Neurobiol Dis 2017; 102:70-80. [PMID: 28193459 DOI: 10.1016/j.nbd.2017.01.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2013] [Revised: 01/17/2017] [Accepted: 01/25/2017] [Indexed: 10/20/2022] Open
Abstract
The alpha2delta-1 subunit (α2δ-1) of voltage-gated calcium channels is a receptor for astrocyte-secreted thrombospondins that promote developmental synaptogenesis. Alpha2delta-1 receptors are upregulated in models of injury-induced peripheral pain and epileptogenic neocortical trauma associated with an enhancement of excitatory synaptic connectivity. These results lead to the hypothesis that overexpression of α2δ-1 alone in neocortex of uninjured transgenic (TG) mice might result in increased excitatory connectivity and consequent cortical hyperexcitability and epileptiform activity. Whole cell recordings from layer V pyramidal neurons in somatosensory cortical slices of TG mice showed increased frequency and amplitude of miniature and spontaneous EPSCs and prolonged bursts of polysynaptic EPSCs. Epileptiform field potentials were evoked in layers II/III and V of brain slices from TG mice, but not controls. Dual immunoreactivity for Vglut-2 and PSD95 showed increased density of close appositions in TG mice compared to controls, suggesting an increased number of excitatory synapses. Video-EEG monitoring showed that 13/13 implanted TG mice aged >P21, but not controls, had frequent abnormal spontaneous epileptiform events, consisting of variable duration, high amplitude bi-hemispheric irregular bursts of delta activity, spikes and sharp waves lasting many seconds, with a variable peak frequency of ~1-3Hz, associated with behavioral arrest. The epileptiform EEG abnormalities and behavioral arrests were reversibly eliminated by treatment with i.p. ethosuximide. Behavioral seizures, consisting of ~15-30s duration episodes of rigid arched tail and head and body extension, followed by loss of balance and falling, frequently occurred in adult TG mice during recovery from isoflurane-induced anesthesia, but were rare in WT mice. Results show that over-expression of α2δ-1 subunits increases cortical excitatory connectivity and leads to neocortical hyperexcitability and epileptiform activity associated with behavioral arrests in adult TG mice. Similar increases in expression of α2δ-1 in models of cortical injury may play an important role in epileptogenesis. SIGNIFICANCE Binding of astrocytic-secreted thrombospondins to their α2δ-1 receptor facilitates excitatory synapse formation and excitatory transmission during cortical development and after injury. Upregulation of α2δ-1 is present in models of injury-induced pain and epileptogenic cortical trauma, along with many other molecular alterations. Here we show that overexpression of α2δ-1 alone in TG mice can enhance excitatory connectivity in neocortex and lead to neural circuit hyperexcitability and episodes of electrographic epileptiform activity, associated with behavioral arrests in transgenic mice. α2δ-1 is the high-affinity receptor for gabapentinoids and a potential target for prophylactic treatment of posttraumatic epilepsy and other disorders in which excessive aberrant excitatory connectivity is a pathophysiological feature.
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Affiliation(s)
- Leonardo C Faria
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Feng Gu
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Isabel Parada
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA
| | - Ben Barres
- Department of Neurobiology, Stanford University, Howard Hughes Medical Institute, Stanford School of Medicine, Stanford, CA 94305-5125, USA
| | - Z David Luo
- Department of Anesthesiology and Perioperative Care, Department of Pharmacology, University of California, Irvine Medical Center, Orange, CA 92868, USA
| | - David A Prince
- Department of Neurology and Neurological Sciences, Stanford University, School of Medicine, Stanford, CA 94305, USA.
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26
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Wu W, Xiong W, Zhang P, Chen L, Fang J, Shields C, Xu XM, Jin X. Increased threshold of short-latency motor evoked potentials in transgenic mice expressing Channelrhodopsin-2. PLoS One 2017; 12:e0178803. [PMID: 28562670 PMCID: PMC5451077 DOI: 10.1371/journal.pone.0178803] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2017] [Accepted: 05/18/2017] [Indexed: 01/28/2023] Open
Abstract
Transgenic mice that express channelrhodopsin-2 or its variants provide a powerful tool for optogenetic study of the nervous system. Previous studies have established that introducing such exogenous genes usually does not alter anatomical, electrophysiological, and behavioral properties of neurons in these mice. However, in a line of Thy1-ChR2-YFP transgenic mice (line 9, Jackson lab), we found that short-latency motor evoked potentials (MEPs) induced by transcranial magnetic stimulation had a longer latency and much lower amplitude than that of wild type mice. MEPs evoked by transcranial electrical stimulation also had a much higher threshold in ChR2 mice, although similar amplitudes could be evoked in both wild and ChR2 mice at maximal stimulation. In contrast, long-latency MEPs evoked by electrically stimulating the motor cortex were similar in amplitude and latency between wild type and ChR2 mice. Whole-cell patch clamp recordings from layer V pyramidal neurons of the motor cortex in ChR2 mice revealed no significant differences in intrinsic membrane properties and action potential firing in response to current injection. These data suggest that corticospinal tract is not accountable for the observed abnormality. Motor behavioral assessments including BMS score, rotarod, and grid-walking test showed no significant differences between the two groups. Because short-latency MEPs are known to involve brainstem reticulospinal tract, while long-latency MEPs mainly involve primary motor cortex and dorsal corticospinal tract, we conclude that this line of ChR2 transgenic mice has normal function of motor cortex and dorsal corticospinal tract, but reduced excitability and responsiveness of reticulospinal tracts. This abnormality needs to be taken into account when using these mice for related optogenetic study.
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Affiliation(s)
- Wei Wu
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Wenhui Xiong
- Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Ping Zhang
- Norton Neuroscience Institute, Norton Healthcare, Louisville, Kentucky, United States of America
| | - Lifang Chen
- Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Acupuncture, Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China
| | - Jianqiao Fang
- Department of Acupuncture, Third Affiliated Hospital of Zhejiang Chinese Medical University, Hangzhou, Zhejiang Province, China.,Zhejiang Chinese Medical University, Hangzhou, China
| | - Christopher Shields
- Norton Neuroscience Institute, Norton Healthcare, Louisville, Kentucky, United States of America
| | - Xiao-Ming Xu
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
| | - Xiaoming Jin
- Department of Neurological Surgery, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Spinal Cord and Brain Injury Research Group, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America.,Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana University School of Medicine, Indianapolis, Indiana, United States of America
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27
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Webster KM, Sun M, Crack P, O'Brien TJ, Shultz SR, Semple BD. Inflammation in epileptogenesis after traumatic brain injury. J Neuroinflammation 2017; 14:10. [PMID: 28086980 PMCID: PMC5237206 DOI: 10.1186/s12974-016-0786-1] [Citation(s) in RCA: 184] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2016] [Accepted: 12/28/2016] [Indexed: 01/02/2023] Open
Abstract
Background Epilepsy is a common and debilitating consequence of traumatic brain injury (TBI). Seizures contribute to progressive neurodegeneration and poor functional and psychosocial outcomes for TBI survivors, and epilepsy after TBI is often resistant to existing anti-epileptic drugs. The development of post-traumatic epilepsy (PTE) occurs in a complex neurobiological environment characterized by ongoing TBI-induced secondary injury processes. Neuroinflammation is an important secondary injury process, though how it contributes to epileptogenesis, and the development of chronic, spontaneous seizure activity, remains poorly understood. A mechanistic understanding of how inflammation contributes to the development of epilepsy (epileptogenesis) after TBI is important to facilitate the identification of novel therapeutic strategies to reduce or prevent seizures. Body We reviewed previous clinical and pre-clinical data to evaluate the hypothesis that inflammation contributes to seizures and epilepsy after TBI. Increasing evidence indicates that neuroinflammation is a common consequence of epileptic seizure activity, and also contributes to epileptogenesis as well as seizure initiation (ictogenesis) and perpetuation. Three key signaling factors implicated in both seizure activity and TBI-induced secondary pathogenesis are highlighted in this review: high-mobility group box protein-1 interacting with toll-like receptors, interleukin-1β interacting with its receptors, and transforming growth factor-β signaling from extravascular albumin. Lastly, we consider age-dependent differences in seizure susceptibility and neuroinflammation as mechanisms which may contribute to a heightened vulnerability to epileptogenesis in young brain-injured patients. Conclusion Several inflammatory mediators exhibit epileptogenic and ictogenic properties, acting on glia and neurons both directly and indirectly influence neuronal excitability. Further research is required to establish causality between inflammatory signaling cascades and the development of epilepsy post-TBI, and to evaluate the therapeutic potential of pharmaceuticals targeting inflammatory pathways to prevent or mitigate the development of PTE.
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Affiliation(s)
- Kyria M Webster
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Mujun Sun
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Peter Crack
- Department of Pharmacology and Therapeutics, The University of Melbourne, Parkville, VIC, 3050, Australia
| | - Terence J O'Brien
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Sandy R Shultz
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia
| | - Bridgette D Semple
- Department of Medicine (The Royal Melbourne Hospital), The University of Melbourne, Kenneth Myer Building, Melbourne Brain Centre, Royal Parade, Parkville, VIC, 3050, Australia.
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28
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Does time heal all wounds? Experimental diffuse traumatic brain injury results in persisting histopathology in the thalamus. Behav Brain Res 2016; 340:137-146. [PMID: 28042008 DOI: 10.1016/j.bbr.2016.12.038] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2016] [Revised: 11/30/2016] [Accepted: 12/28/2016] [Indexed: 11/21/2022]
Abstract
BACKGROUND Thalamic dysfunction has been implicated in overall chronic neurological dysfunction after traumatic brain injury (TBI), however little is known about the underlying histopathology. In experimental diffuse TBI (dTBI), we hypothesize that persisting histopathological changes in the ventral posteromedial (VPM) nucleus of the thalamus is indicative of progressive circuit reorganization. Since circuit reorganization in the VPM impacts the whisker sensory system, the histopathology could explain the development of hypersensitivity to whisker stimulation by 28days post-injury; similar to light and sound hypersensitivity in human TBI survivors. METHODS Adult, male Sprague-Dawley rats underwent craniotomy and midline fluid percussion injury (FPI) (moderate severity; 1.8-2.0atm) or sham surgery. At 1d, 7d, and 28days post-FPI (d FPI) separate experiments confirmed the cytoarchitecture (Giemsa stain) and evaluated neuropathology (silver stain), activated astrocytes (GFAP), neuron morphology (Golgi stain) and microglial morphology (Iba-1) in the VPM. RESULTS Cytoarchitecture was unchanged throughout the time course, similar to previously published data; however, neuropathology and astrocyte activation were significantly increased at 7d and 28d and activated microglia were present at all time points. Neuron morphology was dynamic over the time course with decreased dendritic complexity (fewer branch points; decreased length of processes) at 7d FPI and return to sham values by 28d FPI. CONCLUSIONS These data indicate that dTBI results in persisting thalamic histopathology out to a chronic time point. While these changes can be indicative of either adaptive (recovery) or maladaptive (neurological dysfunction) circuit reorganization, they also provide a potential mechanism by which maladaptive circuit reorganization could contribute to the development of chronic neurological dysfunction. Understanding the processes that mediate circuit reorganization is critical to the development of future therapies for TBI patients.
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LSPS/Optogenetics to Improve Synaptic Connectivity Mapping: Unmasking the Role of Basket Cell-Mediated Feedforward Inhibition. eNeuro 2016; 3:eN-MNT-0142-15. [PMID: 27517089 PMCID: PMC4976301 DOI: 10.1523/eneuro.0142-15.2016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 06/28/2016] [Accepted: 07/15/2016] [Indexed: 12/20/2022] Open
Abstract
Neocortical pyramidal cells (PYRs) receive synaptic inputs from many types of GABAergic interneurons. Connections between parvalbumin (PV)-positive, fast-spiking interneurons (“PV cells”) and PYRs are characterized by perisomatic synapses and high-amplitude, short-latency IPSCs. Here, we present novel methods to study the functional influence of PV cells on layer 5 PYRs using optogenetics combined with laser-scanning photostimulation (LSPS). First, we examined the strength and spatial distribution of PV-to-PYR inputs. To that end, the fast channelrhodopsin variant AAV5-EF1α-DIO-hChR2(E123T)-eYFP (ChETA) was expressed in PV cells in somatosensory cortex of mice using an adeno-associated virus-based viral construct. Focal blue illumination (100–150 µm half-width) was directed through the microscope objective to excite PV cells along a spatial grid covering layers 2–6, while IPSCs were recorded in layer 5 PYRs. The resulting optogenetic input maps showed evoked PV cell inputs originating from an ∼500-μm-diameter area surrounding the recorded PYR. Evoked IPSCs had the short-latency/high-amplitude characteristic of PV cell inputs. Second, we investigated how PV cell activity modulates PYR output in response to synaptic excitation. We expressed halorhodopsin (eNpHR3.0) in PV cells using the same strategy as for ChETA. Yellow illumination hyperpolarized eNpHR3.0-expressing PV cells, effectively preventing action potential generation and thus decreasing the inhibition of downstream targets. Synaptic input maps onto layer 5 PYRs were acquired using standard glutamate-photolysis LSPS either with or without full-field yellow illumination to silence PV cells. The resulting IPSC input maps selectively lacked short-latency perisomatic inputs, while EPSC input maps showed increased connectivity, particularly from upper layers. This indicates that glutamate uncaging LSPS-based excitatory synaptic maps will consistently underestimate connectivity.
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30
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Ping X, Jin X. Chronic Posttraumatic Epilepsy following Neocortical Undercut Lesion in Mice. PLoS One 2016; 11:e0158231. [PMID: 27348225 PMCID: PMC4922553 DOI: 10.1371/journal.pone.0158231] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2016] [Accepted: 06/13/2016] [Indexed: 12/01/2022] Open
Abstract
Posttraumatic epilepsy (PTE) usually develops in a small percentage of patients of traumatic brain injury after a varying latent period. Modeling this chronic neurological condition in rodents is time consuming and inefficient, which constitutes a significant obstacle in studying its mechanism and discovering novel therapeutics for its prevention and treatment. Partially isolated neocortex, or undercut, is known to induce cortical hyperexcitability and epileptiform activity in vitro, and has been used extensively for studying the neurophysiological mechanism of posttraumatic epileptogenesis. However, whether the undercut lesion in rodents causes chronic epileptic seizures has not been systematically characterized. Here we used a miniature telemetry system to continuously monitor electroencephalography (EEG) in adult C57BL mice for up to 3 months after undercut surgery. We found that 50% of animals developed spontaneous seizures between 16–50 days after injury. The mean seizure duration was 8.9±3.6 seconds, and the average seizure frequency was 0.17±0.17 times per day. There was no progression in seizure frequency and duration over the recording period. Video monitoring revealed behavioral arrests and clonic limb movement during seizure attacks. A pentylenetetrazol (PTZ) test further showed increased seizure susceptibility in the undercut mice. We conclude that undercut lesion in mice is a model of chronic PTE that involves spontaneous epileptic seizures.
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Affiliation(s)
- Xingjie Ping
- Department of Anatomy and Cell Biology, Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, 320 W. 15th Street, Indianapolis, Indiana, 46202, United States of America
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Stark Neurosciences Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine, 320 W. 15th Street, Indianapolis, Indiana, 46202, United States of America
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31
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Takahashi DK, Gu F, Parada I, Vyas S, Prince DA. Aberrant excitatory rewiring of layer V pyramidal neurons early after neocortical trauma. Neurobiol Dis 2016; 91:166-81. [PMID: 26956396 DOI: 10.1016/j.nbd.2016.03.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Revised: 02/24/2016] [Accepted: 03/02/2016] [Indexed: 12/27/2022] Open
Abstract
Lesioned neuronal circuits form new functional connections after a traumatic brain injury (TBI). In humans and animal models, aberrant excitatory connections that form after TBI may contribute to the pathogenesis of post-traumatic epilepsy. Partial neocortical isolation ("undercut" or "UC") leads to altered neuronal circuitry and network hyperexcitability recorded in vivo and in brain slices from chronically lesioned neocortex. Recent data suggest a critical period for maladaptive excitatory circuit formation within the first 3days post UC injury (Graber and Prince 1999, 2004; Li et al. 2011, 2012b). The present study focuses on alterations in excitatory connectivity within this critical period. Immunoreactivity (IR) for growth-associated protein (GAP)-43 was increased in the UC cortex 3days after injury. Some GAP-43-expressing excitatory terminals targeted the somata of layer V pyramidal (Pyr) neurons, a domain usually innervated predominantly by inhibitory terminals. Immunocytochemical analysis of pre- and postsynaptic markers showed that putative excitatory synapses were present on somata of these neurons in UC neocortex. Excitatory postsynaptic currents from UC layer V Pyr cells displayed properties consistent with perisomatic inputs and also reflected an increase in the number of synaptic contacts. Laser scanning photostimulation (LSPS) experiments demonstrated reorganized excitatory connectivity after injury within the UC. Concurrent with these changes, spontaneous epileptiform bursts developed in UC slices. Results suggest that aberrant reorganization of excitatory connectivity contributes to early neocortical hyperexcitability in this model. The findings are relevant for understanding the pathophysiology of neocortical post-traumatic epileptogenesis and are important in terms of the timing of potential prophylactic treatments.
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Affiliation(s)
- D Koji Takahashi
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Feng Gu
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Isabel Parada
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - Shri Vyas
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States
| | - David A Prince
- Epilepsy Research Laboratories, Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, CA 94305, United States.
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32
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Ping X, Jin X. Transition from Initial Hypoactivity to Hyperactivity in Cortical Layer V Pyramidal Neurons after Traumatic Brain Injury In Vivo. J Neurotrauma 2016; 33:354-61. [PMID: 26095991 PMCID: PMC4761811 DOI: 10.1089/neu.2015.3913] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Traumatic brain injury (TBI) often results in structural damage and a loss of neurons that is commonly accompanied by early changes in neuronal electrical activity. Loss of neuronal activity has been hypothesized to contribute to post-traumatic epileptogenesis through the regulation of homeostatic plasticity. The existence of activity loss in cortical neurons after TBI and its subsequent transition into hyperactivity over time is not well characterized, however, particularly in models of TBI in vivo. In the current study, changes in neuronal activity in the primary motor cortex after moderate controlled cortical impact (CCI) in mice were studied using a single-unit recording technique in vivo. Recordings were made at different time points after CCI from cortical layer V pyramidal neurons that were within 1-2 mm from the anterior edge of the injured foci. Within 1-4 h after CCI, the frequency of spontaneous single-unit activity depressed significantly, with the mean firing frequency decreasing from 2.59 ± 0.18 Hz in the sham group to 1.05 ± 0.20 Hz of the injured group. The firing frequencies recovered to the normal level at 1 day and 7 days post-CCI, but became significantly higher at 3 days and 14 days post-CCI. The results suggest that TBI caused initial loss of activity in neurons of the perilesional cortical region, which was followed by compensatory recovery and enhancement of activity. These time-dependent changes in neuronal activity may contribute to the development of hyperexcitability through homeostatic activity regulation.
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Affiliation(s)
- Xingjie Ping
- Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine , Indianapolis, Indiana
| | - Xiaoming Jin
- Department of Anatomy and Cell Biology, Stark Neuroscience Research Institute, Indiana Spinal Cord and Brain Injury Research Group, Indiana University School of Medicine , Indianapolis, Indiana
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Chauvette S, Soltani S, Seigneur J, Timofeev I. In vivo models of cortical acquired epilepsy. J Neurosci Methods 2016; 260:185-201. [PMID: 26343530 PMCID: PMC4744568 DOI: 10.1016/j.jneumeth.2015.08.030] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2015] [Revised: 08/24/2015] [Accepted: 08/26/2015] [Indexed: 10/23/2022]
Abstract
The neocortex is the site of origin of several forms of acquired epilepsy. Here we provide a brief review of experimental models that were recently developed to study neocortical epileptogenesis as well as some major results obtained with these methods. Most of neocortical seizures appear to be nocturnal and it is known that neuronal activities reveal high levels of synchrony during slow-wave sleep. Therefore, we start the review with a description of mechanisms of neuronal synchronization and major forms of synchronized normal and pathological activities. Then, we describe three experimental models of seizures and epileptogenesis: ketamine-xylazine anesthesia as feline seizure triggered factor, cortical undercut as cortical penetrating wound model and neocortical kindling. Besides specific technical details describing these models we also provide major features of pathological brain activities recorded during epileptogenesis and seizures. The most common feature of all models of neocortical epileptogenesis is the increased duration of network silent states that up-regulates neuronal excitability and eventually leads to epilepsy.
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Affiliation(s)
- Sylvain Chauvette
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3
| | - Sara Soltani
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3; Department of Psychiatry and Neuroscience, Université Laval, Québec, Canada
| | - Josée Seigneur
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3
| | - Igor Timofeev
- Centre de recherche de l'Institut universitaire en santé mentale de Québec (CRIUSMQ), Local F-6500, 2601 de la Canardière, Québec, QC, Canada G1J2G3; Department of Psychiatry and Neuroscience, Université Laval, Québec, Canada.
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Prince D, Gu F, Parada I. Antiepileptogenic repair of excitatory and inhibitory synaptic connectivity after neocortical trauma. PROGRESS IN BRAIN RESEARCH 2016; 226:209-27. [DOI: 10.1016/bs.pbr.2016.03.013] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
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Abstract
Homeostatic synaptic plasticity (HSP) has been implicated in the development of hyperexcitability and epileptic seizures following traumatic brain injury (TBI). Our in vivo experimental studies in cats revealed that the severity of TBI-mediated epileptogenesis depends on the age of the animal. To characterize mechanisms of these differences, we studied the properties of the TBI-induced epileptogenesis in a biophysically realistic cortical network model with dynamic ion concentrations. After deafferentation, which was induced by dissection of the afferent inputs, there was a reduction of the network activity and upregulation of excitatory connections leading to spontaneous spike-and-wave type seizures. When axonal sprouting was implemented, the seizure threshold increased in the model of young but not the older animals, which had slower or unidirectional homeostatic processes. Our study suggests that age-related changes in the HSP mechanisms are sufficient to explain the difference in the likelihood of seizure onset in young versus older animals. Significance statement: Traumatic brain injury (TBI) is one of the leading causes of intractable epilepsy. Likelihood of developing epilepsy and seizures following severe brain trauma has been shown to increase with age. Specific mechanisms of TBI-related epileptogenesis and how these mechanisms are affected by age remain to be understood. We test a hypothesis that the failure of homeostatic synaptic regulation, a slow negative feedback mechanism that maintains neural activity within a physiological range through activity-dependent modulation of synaptic strength, in older animals may augment TBI-induced epileptogenesis. Our results provide new insight into understanding this debilitating disorder and may lead to novel avenues for the development of effective treatments of TBI-induced epilepsy.
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Temporal progression of evoked field potentials in neocortical slices after unilateral hypoxia-ischemia in perinatal rats: Correlation with cortical epileptogenesis. Neuroscience 2015; 316:232-48. [PMID: 26724579 DOI: 10.1016/j.neuroscience.2015.12.029] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2015] [Revised: 12/14/2015] [Accepted: 12/14/2015] [Indexed: 11/20/2022]
Abstract
Infarcts of the neonatal cerebral cortex can lead to progressive epilepsy, which is characterized by time-dependent increases in seizure frequency after the infarct and by shifts in seizure-onset zones from focal to multi-focal. Using a rat model of unilateral perinatal hypoxia-ischemia (PHI), where long-term seizure monitoring had previously demonstrated progressive epilepsy, evoked field potentials (EFPs) were recorded in layers II/III of coronal neocortical slices to analyze the underlying time-dependent, network-level alterations ipsilateral vs. contralateral to the infarct. At 3weeks after PHI, EFPs ipsilateral to the infarct were normal in artificial cerebrospinal fluid (ACSF); however, after blocking GABAA receptors with bicuculline methiodide (BMI, 30μM), the slices with an infarct were more hyperexcitable than slices without an infarct. At 3weeks, contralateral PHI slices had responses indistinguishable from controls. Six months after PHI in normal ACSF, both ipsi- and contralateral slices from rats with cortical infarcts showed prolonged afterdischarges, which were only slightly augmented in BMI. These data suggest that the early changes after PHI are localized to the ipsilateral infarcted cortex and masked by GABA-mediated inhibition; however, after 6months, progressive epileptogenesis results in generation of robust bilateral hyperexcitability. Because these afterdischarges were only slightly prolonged by BMI, a time-dependent reduction of GABAergic transmission is hypothesized to contribute to the pronounced hyperexcitability at 6months. These changes in the EFPs coincide with the seizure semiology of the epilepsy and therefore offer an opportunity to study the mechanisms underlying this form of progressive pediatric epilepsy.
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Zhao M, Alleva R, Ma H, Daniel AGS, Schwartz TH. Optogenetic tools for modulating and probing the epileptic network. Epilepsy Res 2015; 116:15-26. [PMID: 26354163 PMCID: PMC4567692 DOI: 10.1016/j.eplepsyres.2015.06.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 05/29/2015] [Accepted: 06/14/2015] [Indexed: 12/01/2022]
Abstract
Epilepsy affects roughly 1% of the population worldwide. Although effective treatments with antiepileptic drugs are available, more than 20% of patients have seizures that are refractory to medical therapy and many patients experience adverse effects. Hence, there is a continued need for novel therapies for those patients. A new technique called "optogenetics" may offer a new hope for these refractory patients. Optogenetics is a technology based on the combination of optics and genetics, which can control or record neural activity with light. Following delivery of light-sensitive opsin genes such as channelrhodopsin-2 (ChR2), halorhodopsin (NpHR), and others into brain, excitation or inhibition of specific neurons in precise brain areas can be controlled by illumination at different wavelengths with very high temporal and spatial resolution. Neuromodulation with the optogenetics toolbox have already been shown to be effective at treating seizures in animal models of epilepsy. This review will outline the most recent advances in epilepsy research with optogenetic techniques and discuss how this technology can contribute to our understanding and treatment of epilepsy in the future.
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Affiliation(s)
- Mingrui Zhao
- Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA.
| | - Rose Alleva
- Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA.
| | - Hongtao Ma
- Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA.
| | - Andy G S Daniel
- Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA.
| | - Theodore H Schwartz
- Department of Neurological Surgery, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA; Department of Otolaryngology, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA; Department of Neuroscience, Weill Medical College of Cornell University, New York Presbyterian Hospital, New York, NY 10021, USA.
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Erlandson MA, Manzoni OJ, Bureau I. The Functional Organization of Neocortical Networks Investigated in Slices with Local Field Recordings and Laser Scanning Photostimulation. PLoS One 2015; 10:e0132008. [PMID: 26134668 PMCID: PMC4489676 DOI: 10.1371/journal.pone.0132008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2015] [Accepted: 06/09/2015] [Indexed: 02/07/2023] Open
Abstract
The organization of cortical networks can be investigated functionally in brain slices. Laser scanning photostimulation (LSPS) with glutamate-uncaging allows for a rapid survey of all connections impinging on single cells recorded in patch-clamp. We sought to develop a variant of the method that would allow for a more exhaustive mapping of neuronal networks at every experiment. We found that the extracellular field recordings could be used to detect synaptic responses evoked by LSPS. One to two electrodes were placed in all six cortical layers of barrel cortex successively and maps were computed from the size of synaptic negative local field potentials. The field maps displayed a laminar organization similar to the one observed in maps computed from excitatory postsynaptic currents recorded in patch-clamp mode. Thus, LSPS combined with field recording is an interesting alternative to obtain for every animal tested a comprehensive map of the excitatory intracortical network.
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Affiliation(s)
- Melissa A. Erlandson
- U901 INMED, INSERM, Marseille, France
- UMRS 901, Aix-Marseille University, Marseille, France
| | - Olivier J. Manzoni
- U901 INMED, INSERM, Marseille, France
- UMRS 901, Aix-Marseille University, Marseille, France
| | - Ingrid Bureau
- U901 INMED, INSERM, Marseille, France
- UMRS 901, Aix-Marseille University, Marseille, France
- * E-mail:
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Ramaswamy S, Markram H. Anatomy and physiology of the thick-tufted layer 5 pyramidal neuron. Front Cell Neurosci 2015; 9:233. [PMID: 26167146 PMCID: PMC4481152 DOI: 10.3389/fncel.2015.00233] [Citation(s) in RCA: 107] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2015] [Accepted: 06/08/2015] [Indexed: 11/13/2022] Open
Abstract
The thick-tufted layer 5 (TTL5) pyramidal neuron is one of the most extensively studied neuron types in the mammalian neocortex and has become a benchmark for understanding information processing in excitatory neurons. By virtue of having the widest local axonal and dendritic arborization, the TTL5 neuron encompasses various local neocortical neurons and thereby defines the dimensions of neocortical microcircuitry. The TTL5 neuron integrates input across all neocortical layers and is the principal output pathway funneling information flow to subcortical structures. Several studies over the past decades have investigated the anatomy, physiology, synaptology, and pathophysiology of the TTL5 neuron. This review summarizes key discoveries and identifies potential avenues of research to facilitate an integrated and unifying understanding on the role of a central neuron in the neocortex.
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Affiliation(s)
- Srikanth Ramaswamy
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
| | - Henry Markram
- Blue Brain Project, Ecole Polytechnique Fédérale de Lausanne, Campus Biotech Geneva, Switzerland
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Hånell A, Greer JE, Jacobs KM. Increased Network Excitability Due to Altered Synaptic Inputs to Neocortical Layer V Intact and Axotomized Pyramidal Neurons after Mild Traumatic Brain Injury. J Neurotrauma 2015; 32:1590-8. [PMID: 25789412 DOI: 10.1089/neu.2014.3592] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Mild traumatic brain injury (mTBI) can produce long lasting cognitive dysfunction. There is typically no cell death and only diffuse structural injury after mTBI. Thus, functional changes in intact neurons may contribute to symptoms. We have previously shown altered intrinsic properties of axotomized and intact neurons within 2 d after a central fluid percussion injury in mice expressing yellow fluorescent protein (YFP) that allow identification of axonal state prior to recording. Here, whole-cell patch clamp recordings were used to examine synaptic properties of YFP(+) layer V pyramidal neurons. An increased frequency of spontaneous and miniature excitatory postsynaptic currents (EPSCs) was recorded from axotomized neurons at 1 d and intact neurons at 2 d after injury, likely reflecting an increased number of afferents. This also was reflected in the increased amplitude of the EPSC evoked by local extracellular stimulation for all neurons from injured cortex and increased likelihood of producing an action potential for intact cells. Field potentials recorded in superficial layers after online deep layer stimulation contained a single negative peak in controls but multiple negative peaks in injured tissue. The amplitude of this evoked negativity was significantly larger than controls over a series of stimulus intensities at both the 1 d and 2 d survival times. Interictal-like spikes never occurred in the field potential recordings from controls but were observed in 20-80% of stimulus presentations in injured cortex. Together, these results suggest an overall increase in network excitability and the production of particularly powerful (intact) neurons that have both increased intrinsic and synaptic excitability.
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Affiliation(s)
- Anders Hånell
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
| | - John E Greer
- 2 Department of Neurosurgery, Virginia Commonwealth University , Richmond, Virginia
| | - Kimberle M Jacobs
- 1 Department of Anatomy and Neurobiology, Virginia Commonwealth University , Richmond, Virginia
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Kratz MB, Manis PB. Spatial organization of excitatory synaptic inputs to layer 4 neurons in mouse primary auditory cortex. Front Neural Circuits 2015; 9:17. [PMID: 25972787 PMCID: PMC4413692 DOI: 10.3389/fncir.2015.00017] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2015] [Accepted: 04/07/2015] [Indexed: 12/28/2022] Open
Abstract
Layer 4 (L4) of primary auditory cortex (A1) receives a tonotopically organized projection from the medial geniculate nucleus of the thalamus. However, individual neurons in A1 respond to a wider range of sound frequencies than would be predicted by their thalamic input, which suggests the existence of cross-frequency intracortical networks. We used laser scanning photostimulation and uncaging of glutamate in brain slices of mouse A1 to characterize the spatial organization of intracortical inputs to L4 neurons. Slices were prepared to include the entire tonotopic extent of A1. We find that L4 neurons receive local vertically organized (columnar) excitation from layers 2 through 6 (L6) and horizontally organized excitation primarily from L4 and L6 neurons in regions centered ~300–500 μm caudal and/or rostral to the cell. Excitatory horizontal synaptic connections from layers 2 and 3 were sparse. The origins of horizontal projections from L4 and L6 correspond to regions in the tonotopic map that are approximately an octave away from the target cell location. Such spatially organized lateral connections may contribute to the detection and processing of auditory objects with specific spectral structures.
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Affiliation(s)
- Megan B Kratz
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; The Curriculum in Neurobiology, University of North Carolina Chapel Hill, NC, USA
| | - Paul B Manis
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill Chapel Hill, NC, USA ; The Curriculum in Neurobiology, University of North Carolina Chapel Hill, NC, USA ; Department of Cell Biology and Physiology, University of North Carolina Chapel Hill, NC, USA
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Paz JT, Huguenard JR. Microcircuits and their interactions in epilepsy: is the focus out of focus? Nat Neurosci 2015; 18:351-9. [PMID: 25710837 DOI: 10.1038/nn.3950] [Citation(s) in RCA: 204] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 01/16/2015] [Indexed: 12/11/2022]
Abstract
Epileptic seizures represent dysfunctional neural networks dominated by excessive and/or hypersynchronous activity. Recent progress in the field has outlined two concepts regarding mechanisms of seizure generation, or ictogenesis. First, all seizures, even those associated with what have historically been thought of as 'primary generalized' epilepsies, appear to originate in local microcircuits and then propagate from that initial ictogenic zone. Second, seizures propagate through cerebral networks and engage microcircuits in distal nodes, a process that can be weakened or even interrupted by suppressing activity in such nodes. We describe various microcircuit motifs, with a special emphasis on one that has been broadly implicated in several epilepsies: feed-forward inhibition. Furthermore, we discuss how, in the dynamic network in which seizures propagate, focusing on circuit 'choke points' remote from the initiation site might be as important as that of the initial dysfunction, the seizure 'focus'.
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Affiliation(s)
- Jeanne T Paz
- Gladstone Institutes and University of California, San Francisco, California, USA
| | - John R Huguenard
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Stanford, California, USA
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Abstract
All brain normal or pathological activities occur in one of the states of vigilance: wake, slow-wave sleep, or REM sleep. Neocortical seizures preferentially occur during slow-wave sleep. We provide a description of neuronal behavior and mechanisms mediating such a behavior within neocortex taking place in natural states of vigilance as well as during seizures pointing to similarities and differences exhibited during sleep and seizures. A concept of epileptic focus is described using a model of cortical undercut, because in that model, the borders of the focus are well defined. In this model, as in other models of acquired epilepsy, the main factor altering excitability is deafferentation, which upregulates neuronal excitability that promotes generation of seizures. Periods of disfacilitation recorded during slow-wave sleep further upregulate neuronal excitability. It appears that the state of neurons and neuronal network in the epileptic focus produced by deafferentation are such that seizures cannot be generated there. Instead, seizures always start around the perimeter of the undercut cortex. Therefore, we define these areas as the seizure focus. In this zone, neuronal connectivity and excitability are moderately enhanced, lowering the threshold for seizure generation.
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Weissberg I, Wood L, Kamintsky L, Vazquez O, Milikovsky DZ, Alexander A, Oppenheim H, Ardizzone C, Becker A, Frigerio F, Vezzani A, Buckwalter MS, Huguenard JR, Friedman A, Kaufer D. Albumin induces excitatory synaptogenesis through astrocytic TGF-β/ALK5 signaling in a model of acquired epilepsy following blood-brain barrier dysfunction. Neurobiol Dis 2015; 78:115-25. [PMID: 25836421 DOI: 10.1016/j.nbd.2015.02.029] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2014] [Revised: 01/07/2015] [Accepted: 02/19/2015] [Indexed: 01/26/2023] Open
Abstract
Post-injury epilepsy (PIE) is a common complication following brain insults, including ischemic, and traumatic brain injuries. At present, there are no means to identify the patients at risk to develop PIE or to prevent its development. Seizures can occur months or years after the insult, do not respond to anti-seizure medications in over third of the patients, and are often associated with significant neuropsychiatric morbidities. We have previously established the critical role of blood-brain barrier dysfunction in PIE, demonstrating that exposure of brain tissue to extravasated serum albumin induces activation of inflammatory transforming growth factor beta (TGF-β) signaling in astrocytes and eventually seizures. However, the link between the acute astrocytic inflammatory responses and reorganization of neural networks that underlie recurrent spontaneous seizures remains unknown. Here we demonstrate in vitro and in vivo that activation of the astrocytic ALK5/TGF-β-pathway induces excitatory, but not inhibitory, synaptogenesis that precedes the appearance of seizures. Moreover, we show that treatment with SJN2511, a specific ALK5/TGF-β inhibitor, prevents synaptogenesis and epilepsy. Our findings point to astrocyte-mediated synaptogenesis as a key epileptogenic process and highlight the manipulation of the TGF-β-pathway as a potential strategy for the prevention of PIE.
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Affiliation(s)
- Itai Weissberg
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Lydia Wood
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140, USA
| | - Lyn Kamintsky
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Oscar Vazquez
- Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-3140, USA
| | - Dan Z Milikovsky
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel
| | - Allyson Alexander
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - Hannah Oppenheim
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140, USA
| | - Carolyn Ardizzone
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140, USA
| | - Albert Becker
- Department of Neuropathology, University of Bonn Medical Center, Bonn 53105, Germany
| | - Federica Frigerio
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Annamaria Vezzani
- Department of Neuroscience, IRCCS-Istituto di Ricerche Farmacologiche "Mario Negri", Milan, Italy
| | - Marion S Buckwalter
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - John R Huguenard
- Department of Neurology and Neurological Sciences, Stanford University, Stanford, CA, USA
| | - Alon Friedman
- Departments of Physiology and Cell Biology, Cognitive and Brain Sciences, Zlotowski Center for Neuroscience, Ben-Gurion University of the Negev, Beer-Sheva 84105, Israel.
| | - Daniela Kaufer
- Department of Integrative Biology, University of California, Berkeley, Berkeley, CA 94720-3140, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720-3140, USA; Canadian Institute for Advanced Research (CIFAR) Program in Child and Brain Development Toronto, ON M5G 1Z8, Canada.
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Ehrens D, Sritharan D, Sarma SV. Closed-loop control of a fragile network: application to seizure-like dynamics of an epilepsy model. Front Neurosci 2015; 9:58. [PMID: 25784851 PMCID: PMC4347430 DOI: 10.3389/fnins.2015.00058] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2014] [Accepted: 02/09/2015] [Indexed: 11/13/2022] Open
Abstract
It has recently been proposed that the epileptic cortex is fragile in the sense that seizures manifest through small perturbations in the synaptic connections that render the entire cortical network unstable. Closed-loop therapy could therefore entail detecting when the network goes unstable, and then stimulating with an exogenous current to stabilize the network. In this study, a non-linear stochastic model of a neuronal network was used to simulate both seizure and non-seizure activity. In particular, synaptic weights between neurons were chosen such that the network's fixed point is stable during non-seizure periods, and a subset of these connections (the most fragile) were perturbed to make the same fixed point unstable to model seizure events; and, the model randomly transitions between these two modes. The goal of this study was to measure spike train observations from this epileptic network and then apply a feedback controller that (i) detects when the network goes unstable, and then (ii) applies a state-feedback gain control input to the network to stabilize it. The stability detector is based on a 2-state (stable, unstable) hidden Markov model (HMM) of the network, and detects the transition from the stable mode to the unstable mode from using the firing rate of the most fragile node in the network (which is the output of the HMM). When the unstable mode is detected, a state-feedback gain is applied to generate a control input to the fragile node bringing the network back to the stable mode. Finally, when the network is detected as stable again, the feedback control input is switched off. High performance was achieved for the stability detector, and feedback control suppressed seizures within 2 s after onset.
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Affiliation(s)
- Daniel Ehrens
- Neuromedical Control Systems Lab, Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Duluxan Sritharan
- Neuromedical Control Systems Lab, Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
| | - Sridevi V Sarma
- Neuromedical Control Systems Lab, Biomedical Engineering, Institute for Computational Medicine, Johns Hopkins University Baltimore, MD, USA
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Zhao M, McGarry LM, Ma H, Harris S, Berwick J, Yuste R, Schwartz TH. Optical triggered seizures using a caged 4-Aminopyridine. Front Neurosci 2015; 9:25. [PMID: 25698919 PMCID: PMC4316705 DOI: 10.3389/fnins.2015.00025] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2014] [Accepted: 01/14/2015] [Indexed: 11/16/2022] Open
Abstract
Animal models of epilepsy are critical not only for understanding the fundamental mechanism of epilepsy but also for testing the efficacy of new antiepileptic drugs and novel therapeutic interventions. Photorelease of caged molecules is widely used in biological research to control pharmacologic events with high spatio-temporal resolution. We developed a technique for in vivo optical triggering of neocortical seizures using a novel caged compound based on ruthenium photochemistry (RuBi-4AP). Epileptiform events in mouse cortex were induced with blue light in both whole brain and focal illumination. Multi-electrode array recording and optical techniques were used to characterize the propagation of these epileptic events, including interictal spikes, polyspikes, and ictal discharges. These results demonstrate a novel optically-triggered seizure model, with high spatio-temporal control, that could have widespread application in the investigation of ictal onset, propagation and to develop novel light-based therapeutic interventions.
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Affiliation(s)
- Mingrui Zhao
- Department of Neurological Surgery, Brain and Mind Center, New York Presbyterian Hospital, Weill Medical College of Cornell UniversityNew York, NY, USA
| | - Laura M. McGarry
- Department of Biological Sciences, Columbia UniversityNew York, NY, USA
| | - Hongtao Ma
- Department of Neurological Surgery, Brain and Mind Center, New York Presbyterian Hospital, Weill Medical College of Cornell UniversityNew York, NY, USA
| | - Samuel Harris
- Department of Neurological Surgery, Brain and Mind Center, New York Presbyterian Hospital, Weill Medical College of Cornell UniversityNew York, NY, USA
- Department of Psychology, University of SheffieldSheffield, UK
| | - Jason Berwick
- Department of Psychology, University of SheffieldSheffield, UK
| | - Rafael Yuste
- Department of Biological Sciences, Columbia UniversityNew York, NY, USA
| | - Theodore H. Schwartz
- Department of Neurological Surgery, Brain and Mind Center, New York Presbyterian Hospital, Weill Medical College of Cornell UniversityNew York, NY, USA
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47
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Shafi MM, Vernet M, Klooster D, Chu CJ, Boric K, Barnard ME, Romatoski K, Westover MB, Christodoulou JA, Gabrieli JDE, Whitfield-Gabrieli S, Pascual-Leone A, Chang BS. Physiological consequences of abnormal connectivity in a developmental epilepsy. Ann Neurol 2015; 77:487-503. [PMID: 25858773 DOI: 10.1002/ana.24343] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2014] [Revised: 11/26/2014] [Accepted: 12/07/2014] [Indexed: 12/31/2022]
Abstract
OBJECTIVE Many forms of epilepsy are associated with aberrant neuronal connections, but the relationship between such pathological connectivity and the underlying physiological predisposition to seizures is unclear. We sought to characterize the cortical excitability profile of a developmental form of epilepsy known to have structural and functional connectivity abnormalities. METHODS We employed transcranial magnetic stimulation (TMS) with simultaneous electroencephalographic (EEG) recording in 8 patients with epilepsy from periventricular nodular heterotopia and matched healthy controls. We used connectivity imaging findings to guide TMS targeting and compared the evoked responses to single-pulse stimulation from different cortical regions. RESULTS Heterotopia patients with active epilepsy demonstrated a relatively augmented late cortical response that was greater than that of matched controls. This abnormality was specific to cortical regions with connectivity to subcortical heterotopic gray matter. Topographic mapping of the late response differences showed distributed cortical networks that were not limited to the stimulation site, and source analysis in 1 subject revealed that the generator of abnormal TMS-evoked activity overlapped with the spike and seizure onset zone. INTERPRETATION Our findings indicate that patients with epilepsy from gray matter heterotopia have altered cortical physiology consistent with hyperexcitability, and that this abnormality is specifically linked to the presence of aberrant connectivity. These results support the idea that TMS-EEG could be a useful biomarker in epilepsy in gray matter heterotopia, expand our understanding of circuit mechanisms of epileptogenesis, and have potential implications for therapeutic neuromodulation in similar epileptic conditions associated with deep lesions.
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Affiliation(s)
- Mouhsin M Shafi
- Berenson-Allen Center for Noninvasive Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA; Comprehensive Epilepsy Center, Department of Neurology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
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48
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Ehrens D, Sritharan D, Sarma SV. Instability detector of a fragile neural network: application to seizure detection in epilepsy. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2015; 2014:6569-72. [PMID: 25571501 DOI: 10.1109/embc.2014.6945133] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
It has recently been proposed that the epileptic cortex is fragile in the sense that seizures manifest through small perturbations in the synaptic connections that render the entire cortical network unstable. Therefore, one method for detecting seizures is to detect when the neuronal network has gone unstable. This is important for implementing a closed-loop therapy to suppress seizures. In this paper, we consider a widely used nonlinear stochastic model of a neuronal network, and assume that spiking dynamics during non-seizure periods correspond to certain synaptic connections that render its fixed point stable. We then apply a minimum energy perturbation theory we recently developed for networks to determine the changes in the most fragile node's synaptic connections that make the same fixed point unstable (our model during seizure). Then a detector is designed as follows. First a 2-state HMM is constructed (stable=state 1 and unstable=state 2) with fixed state transition probabilities, where the output observation is the firing rate of the most fragile node in the network. The output density functions are assumed to be Gaussian with parameters computed using maximum likelihood estimation on data generated from the nonlinear network model in each state. Then, to detect a transition from stable to unstable, spiking activity is simulated in all nodes from the nonlinear model. The detector first measures the firing rate of the fragile node, and computes the derivative of the cumulative likelihood ratio of the observed firing rate from the HMM's output distributions. When the derivative exceeds a certain threshold, a transition to the unstable state is detected. Various thresholds were tested when firing rate was computed by averaging over a different number of windows of different lengths. High performance was achieved and a tradeoff was found between the accuracy of the detector and the detection delay.
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49
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Imbrosci B, Neitz A, Mittmann T. Focal cortical lesions induce bidirectional changes in the excitability of fast spiking and non fast spiking cortical interneurons. PLoS One 2014; 9:e111105. [PMID: 25347396 PMCID: PMC4210267 DOI: 10.1371/journal.pone.0111105] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2014] [Accepted: 09/28/2014] [Indexed: 11/29/2022] Open
Abstract
A physiological brain function requires neuronal networks to operate within a well-defined range of activity. Indeed, alterations in neuronal excitability have been associated with several pathological conditions, ranging from epilepsy to neuropsychiatric disorders. Changes in inhibitory transmission are known to play a key role in the development of hyperexcitability. However it is largely unknown whether specific interneuronal subpopulations contribute differentially to such pathological condition. In the present study we investigated functional alterations of inhibitory interneurons embedded in a hyperexcitable cortical circuit at the border of chronically induced focal lesions in mouse visual cortex. Interestingly, we found opposite alterations in the excitability of non fast-spiking (Non Fs) and fast-spiking (Fs) interneurons in acute cortical slices from injured animals. Non Fs interneurons displayed a depolarized membrane potential and a higher frequency of spontaneous excitatory postsynaptic currents (sEPSCs). In contrast, Fs interneurons showed a reduced sEPSCs amplitude. The observed downscaling of excitatory synapses targeting Fs interneurons may prevent the recruitment of this specific population of interneurons to the hyperexcitable network. This mechanism is likely to seriously affect neuronal network function and to exacerbate hyperexcitability but it may be important to protect this particular vulnerable population of GABAegic neurons from excitotoxicity.
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Affiliation(s)
- Barbara Imbrosci
- Institute of Physiology, University Medical Center of the Johannes-Gutenberg University Mainz, Mainz, Germany
- * E-mail: (BI); (TM)
| | - Angela Neitz
- Institute of Physiology, University Medical Center of the Johannes-Gutenberg University Mainz, Mainz, Germany
| | - Thomas Mittmann
- Institute of Physiology, University Medical Center of the Johannes-Gutenberg University Mainz, Mainz, Germany
- * E-mail: (BI); (TM)
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50
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Changes in long-range connectivity and neuronal reorganization in partial cortical deafferentation model of epileptogenesis. Neuroscience 2014; 284:153-164. [PMID: 25304932 DOI: 10.1016/j.neuroscience.2014.09.079] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 09/22/2014] [Accepted: 09/30/2014] [Indexed: 12/22/2022]
Abstract
Severe brain injuries can trigger epileptogenesis, a latent period that eventually leads to epilepsy. Previous studies have demonstrated that changes in local connectivity between cortical neurons are a part of the epileptogenic processes. In the present study we aimed to investigate whether changes in long-range connectivity are also involved in epileptogenesis. We performed a large unilateral transection (undercut) of the white matter below the suprasylvian gyrus in cats. After about 2 months, we either injected retrograde tracer (cholera toxin, sub-unit B, CTB) or performed Golgi staining. We analyzed distribution of retrogradely labeled neurons, counted dendritic spines in the neocortex (Golgi staining), and analyzed dendritic orientation in control conditions and after the injury. We found a significant increase in the number of detected cells at the frontal parts of the injured hemisphere, which suggests that the process of axonal sprouting occurs in the deafferented area. The increase in the number of retrogradely stained neurons was accompanied with a significant decrease in neocortical spine density in the undercut area, a reduction in vertical and an increase in horizontal orientation of neuronal processes. The present study shows global morphological changes underlying epileptogenesis. An increased connectivity in the injured cortical regions accompanied with a decrease in spine density suggests that excitatory synapses might be formed on dendritic shafts, which probably contributes to the altered neuronal excitability that was described in previous studies on epileptogenesis.
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